Flavin mononucleotide

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_span

{"source_cache": "artifacts/dim-research/19884324.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214", "start_char": 0, "end_char": 1738, "text_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214"}

experimental_model

Recombinant protein and engineered bacterial coexpression

exposure

POR mutation and added FMN

limitations

In-vitro rescue of one mutant; not a dietary-riboflavin deficiency experiment or evidence that FMN reverses a DIM-drug interaction.

nutrient_topic

Diindolylmethane (DIM) research collection; topical membership is not evidence of a direct dietary effect. · 3,3'-Diindolylmethane / DIM

organism

Human POR Y181D and human CYP1A2 in engineered systems

plain_language

A specific cofactor-binding defect could be partly rescued in the assay.

primary_references

[dim-p19884324] Human cytochrome P450 oxidoreductase deficiency caused by the Y181D mutation: molecular consequences and rescue of defect. (2010). https://pubmed.ncbi.nlm.nih.gov/19884324/ DOI: 10.1124/dmd.109.030445

tissue_or_cell_type

FMN-dependent electron transfer

trigger_kind

machinery_impairment Imported condition classification; unverified.

Diindolylmethane (DIM): formation, receptor signaling, metabolism and drug interactions (2026-09-17) · lines 285–296

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant protein and engineered bacterial coexpression · source_derived_draft · unverified_draft

### dim-por-fmn-rescue Added FMN restored CYP1A2 ethoxyresorufin activity in POR Y181D membranes to 37% of the wild-type system. Condition category: machinery_impairment nutrient_topic: Diindolylmethane (DIM) research collection; topical membership is not evidence of a direct dietary effect. plain_language: A specific cofactor-binding defect could be partly rescued in the assay. organism: Human POR Y181D and human CYP1A2 in engineered systems tissue_or_cell_type: FMN-dependent electron transfer experimental_model: Recombinant protein and engineered bacterial coexpression limitations: In-vitro rescue of one mutant; not a dietary-riboflavin deficiency experiment or evidence that FMN reverses a DIM-drug interaction. exposure: POR mutation and added FMN evidence_span: {"source_cache": "artifacts/dim-research/19884324.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214", "start_char": 0, "end_char": 1738, "text_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214"} [dim-p19884324] Human cytochrome P450 oxidoreductase deficiency caused by the Y181D mutation: molecular consequences and rescue of defect. (2010). https://pubmed.ncbi.nlm.nih.gov/19884324/ DOI: 10.1124/dmd.109.030445

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_spans

[{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC2440658", "locator": "HTML article p", "paragraph_index": 19, "char_start": 0, "char_end": 1242, "evidence_access": "full-text"}]

experimental_model

Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution.

exposure

10 micromolar FMN after NADH/respiratory blockade at pH 10.

limitations

pH 10 treatment; not a test of dietary deficiency or oral supplementation.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Bos taurus

plain_language

Putting the correct flavin back restored this experimentally inactivated respiratory enzyme.

primary_references

[gostimskaya-2007-complex-i-fmn] Reversible dissociation of flavin mononucleotide from the mammalian membrane-bound NADH: ubiquinone oxidoreductase (complex I) (2007). https://pubmed.ncbi.nlm.nih.gov/18037377/ DOI: 10.1016/j.febslet.2007.11.048

tissue_or_cell_type

Heart submitochondrial particles

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 570–581

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution. · source_derived_draft · unverified_draft

### b2-met-complex-i-fmn-reconstitution FMN restored rotenone-sensitive NADH:quinone reductase activity after alkaline reductive inactivation of bovine membrane-bound complex I. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Putting the correct flavin back restored this experimentally inactivated respiratory enzyme. organism: Bos taurus tissue_or_cell_type: Heart submitochondrial particles experimental_model: Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution. limitations: pH 10 treatment; not a test of dietary deficiency or oral supplementation. exposure: 10 micromolar FMN after NADH/respiratory blockade at pH 10. evidence_spans: [{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC2440658", "locator": "HTML article p", "paragraph_index": 19, "char_start": 0, "char_end": 1242, "evidence_access": "full-text"}] [gostimskaya-2007-complex-i-fmn] Reversible dissociation of flavin mononucleotide from the mammalian membrane-bound NADH: ubiquinone oxidoreductase (complex I) (2007). https://pubmed.ncbi.nlm.nih.gov/18037377/ DOI: 10.1016/j.febslet.2007.11.048

cross_nutrient

B2-FMN is a cofactor for B6 activation.

evidence_location

Results: kinetic properties; Table 1; FMN-binding structure

experimental_model

Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C.

exposure

Purified-enzyme assay

limitations

Biochemical evidence does not establish a dietary threshold or supplementation benefit.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

PNPO uses the FMN form of vitamin B2.

primary_references

[musayev2003] Structure and properties of recombinant human pyridoxine 5'-phosphate oxidase. (2003). https://pubmed.ncbi.nlm.nih.gov/12824491/ DOI: 10.1110/ps.0356203

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1136–1148

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C. · source_derived_draft · unverified_draft

### b2-pnpo-fmn-binding The human PNPO structure localized tightly bound FMN at the conserved catalytic site of the homodimer. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: PNPO uses the FMN form of vitamin B2. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C. limitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit. exposure: Purified-enzyme assay cross_nutrient: B2-FMN is a cofactor for B6 activation. evidence_location: Results: kinetic properties; Table 1; FMN-binding structure [musayev2003] Structure and properties of recombinant human pyridoxine 5'-phosphate oxidase. (2003). https://pubmed.ncbi.nlm.nih.gov/12824491/ DOI: 10.1110/ps.0356203

evidence_location

Abstract; intestinal fractionation and EDTA competition experiments

experimental_model

Rat mucosal fractionation, hydrolase assays and radiolabeled-riboflavin uptake in everted intestinal rings

exposure

Flavin coenzymes with or without EDTA during tracer uptake.

limitations

Rat ex vivo evidence; molecular identities of the hydrolases were not established.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Rattus norvegicus

plain_language

Dietary FMN can supply absorbable riboflavin after intestinal cleavage.

primary_references

[transport-diet-1982] FMN phosphatase and FAD pyrophosphatase in rat intestinal brush borders: role in intestinal absorption of dietary riboflavin. (1982). https://doi.org/10.1093/jn/112.2.263 DOI: 10.1093/jn/112.2.263

tissue_or_cell_type

Small-intestinal mucosa

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 111–122

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Rat mucosal fractionation, hydrolase assays and radiolabeled-riboflavin uptake in everted intestinal rings · source_derived_draft · unverified_draft

### transport-dietary-fmn-hydrolysis Rat brush-border preparations released free riboflavin from FMN; inhibiting coenzyme hydrolysis reduced its competition with tracer riboflavin uptake. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Dietary FMN can supply absorbable riboflavin after intestinal cleavage. organism: Rattus norvegicus tissue_or_cell_type: Small-intestinal mucosa experimental_model: Rat mucosal fractionation, hydrolase assays and radiolabeled-riboflavin uptake in everted intestinal rings limitations: Rat ex vivo evidence; molecular identities of the hydrolases were not established. exposure: Flavin coenzymes with or without EDTA during tracer uptake. evidence_location: Abstract; intestinal fractionation and EDTA competition experiments [transport-diet-1982] FMN phosphatase and FAD pyrophosphatase in rat intestinal brush borders: role in intestinal absorption of dietary riboflavin. (1982). https://doi.org/10.1093/jn/112.2.263 DOI: 10.1093/jn/112.2.263

evidence_span

{"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"}

experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

A second B2-derived flavin participates in the enzyme system.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 541–552

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-fmn The human eNOS preparation contained approximately 0.79 FMN equivalents per subunit. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: A second B2-derived flavin participates in the enzyme system. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

cross_nutrient

true

evidence_location

Primary Results, wild-type structure and cofactor-binding sites; Methods flavin extraction/HPLC.

experimental_model

Human POR structure and flavin-content analysis

exposure

Recombinant N-terminally truncated human POR; X-ray structure and HPLC flavin assays.

limitations

The structural study did not measure vitamin D outcomes after riboflavin dosing; linkage to CYP2R1 comes from the separate direct reconstitution record.

nutrient

Vitamin D2 and D3 · Vitamin D2 and D3

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens protein

plain_language

POR carries a FMN cofactor derived from vitamin B2.

primary_references

[xia2011] Structural basis for human NADPH-cytochrome P450 oxidoreductase deficiency. (2011). https://pubmed.ncbi.nlm.nih.gov/21808038/ DOI: 10.1073/pnas.1106632108

tissue_or_cell_type

POR cofactor-binding domain

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 422–435

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human POR structure and flavin-content analysis · source_derived_draft · unverified_draft

### vd-act-por-fmn Crystallography and extracted-flavin analysis identified FMN bound to recombinant human POR. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: POR carries a FMN cofactor derived from vitamin B2. organism: Homo sapiens protein tissue_or_cell_type: POR cofactor-binding domain experimental_model: Human POR structure and flavin-content analysis limitations: The structural study did not measure vitamin D outcomes after riboflavin dosing; linkage to CYP2R1 comes from the separate direct reconstitution record. exposure: Recombinant N-terminally truncated human POR; X-ray structure and HPLC flavin assays. cross_nutrient: true evidence_location: Primary Results, wild-type structure and cofactor-binding sites; Methods flavin extraction/HPLC. nutrient: Vitamin D2 and D3 [xia2011] Structural basis for human NADPH-cytochrome P450 oxidoreductase deficiency. (2011). https://pubmed.ncbi.nlm.nih.gov/21808038/ DOI: 10.1073/pnas.1106632108

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

A B6-activation disorder directly disrupts B2-cofactor binding.

evidence_location

Results: Table 3 and Fig 1; Table 2 and Fig 2

experimental_model

Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure.

exposure

Purified-enzyme assay

limitations

Biochemical evidence does not establish a dietary threshold or supplementation benefit.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

The genetic substitution weakens FMN binding.

primary_references

[musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1206–1218

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. · source_derived_draft · unverified_draft

### b2-pnpo-r229w-fmn-affinity R229W PNPO had an FMN dissociation constant approximately 50-fold higher than wild type in apoenzyme fluorescence titrations. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The genetic substitution weakens FMN binding. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. limitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit. exposure: Purified-enzyme assay cross_nutrient: A B6-activation disorder directly disrupts B2-cofactor binding. evidence_location: Results: Table 3 and Fig 1; Table 2 and Fig 2 [musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372

evidence_location

FAD synthesis and reverse pyrophosphorolysis assays

experimental_model

Purified recombinant human FADS2 catalytic assays

exposure

ATP and FMN in FAD-synthesis assays.

limitations

Adenylylation is distinct from RFK phosphorylation; reaction products should not be conflated.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

FLAD1 performs the second activation step, making FAD from FMN.

primary_references

[transport-fads2-2011] Human FAD synthase (isoform 2): a component of the machinery that delivers FAD to apo-flavoproteins. (2011). https://pubmed.ncbi.nlm.nih.gov/21951714/ DOI: 10.1111/j.1742-4658.2011.08368.x

tissue_or_cell_type

Purified protein

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 320–331

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human FADS2 catalytic assays · source_derived_draft · unverified_draft

### transport-flad1-adenylylation Human FAD synthase isoform 2 adenylylates FMN with ATP to form FAD and pyrophosphate. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: FLAD1 performs the second activation step, making FAD from FMN. organism: Homo sapiens tissue_or_cell_type: Purified protein experimental_model: Purified recombinant human FADS2 catalytic assays limitations: Adenylylation is distinct from RFK phosphorylation; reaction products should not be conflated. exposure: ATP and FMN in FAD-synthesis assays. evidence_location: FAD synthesis and reverse pyrophosphorolysis assays [transport-fads2-2011] Human FAD synthase (isoform 2): a component of the machinery that delivers FAD to apo-flavoproteins. (2011). https://pubmed.ncbi.nlm.nih.gov/21951714/ DOI: 10.1111/j.1742-4658.2011.08368.x

cross_nutrient

true

evidence_span

{"source_cache": "artifacts/iodine-synthesis-sources/25395621.txt", "start_char": 14596, "end_char": 15366, "text_sha256": "5f3959109e358adaddae3ea78c716d16316c28f6fb4153ad5696bae7b1ed733e", "text_characters": 770, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."}

experimental_model

Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration

exposure

Human soluble IYD crystallized alone or with 3-iodo-L-tyrosine.

limitations

Cofactor structure; no riboflavin restriction or supplementation study.

nutrient_topic

Iodine research collection; topical membership is not evidence of a direct dietary effect. · Iodine

organism

Homo sapiens recombinant protein

plain_language

IYD uses the vitamin-B2-derived cofactor FMN to handle iodotyrosine.

primary_references

[iodine-syn-iyd2015] A switch between one- and two-electron chemistry of the human flavoprotein iodotyrosine deiodinase is controlled by substrate. (2015). https://pubmed.ncbi.nlm.nih.gov/25395621/ DOI: 10.1074/jbc.m114.605964

tissue_or_cell_type

Purified soluble IYD

Iodine: thyroid hormone production, deficiency, excess and nutrient interactions (2026-09-17) · lines 702–714

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration · source_derived_draft · unverified_draft

### iodine-syn-iyd-fmn-binding Human IYD crystal structures show one bound FMN per polypeptide, with iodotyrosine contacting its isoalloxazine ring in the substrate complex. Condition category: normal nutrient_topic: Iodine research collection; topical membership is not evidence of a direct dietary effect. plain_language: IYD uses the vitamin-B2-derived cofactor FMN to handle iodotyrosine. organism: Homo sapiens recombinant protein tissue_or_cell_type: Purified soluble IYD experimental_model: Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration limitations: Cofactor structure; no riboflavin restriction or supplementation study. exposure: Human soluble IYD crystallized alone or with 3-iodo-L-tyrosine. cross_nutrient: true evidence_span: {"source_cache": "artifacts/iodine-synthesis-sources/25395621.txt", "start_char": 14596, "end_char": 15366, "text_sha256": "5f3959109e358adaddae3ea78c716d16316c28f6fb4153ad5696bae7b1ed733e", "text_characters": 770, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."} [iodine-syn-iyd2015] A switch between one- and two-electron chemistry of the human flavoprotein iodotyrosine deiodinase is controlled by substrate. (2015). https://pubmed.ncbi.nlm.nih.gov/25395621/ DOI: 10.1074/jbc.m114.605964

cross_nutrient

true

experimental_model

Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution

exposure

Purified human recombinant protein spectroscopy and cofactor characterization.

limitations

Direct enzyme-cofactor evidence; the study did not test dietary B2 deficiency, oral riboflavin rescue, or a universal FMN threshold. FMN origin from B2 is shared nutrient context, not a newly demonstrated dietary effect.

nutrient_topic

Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect. · Pantothenate (vitamin B5)

organism

Homo sapiens

plain_language

The CoA pathway contains a direct biochemical connection to the B2 cofactor FMN.

primary_references

[b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200

tissue_or_cell_type

Purified recombinant protein; no intact tissue

Pantothenic acid (vitamin B5): coenzyme A, deficiency and nutrient interactions (2026-09-17) · lines 561–572

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution · source_derived_draft · unverified_draft

### b5-bio-ppcdc-fmn Purified recombinant human PPCDC showed flavin-like absorbance maxima at 382 and 458 nm and approximately equimolar FMN association. Condition category: normal nutrient_topic: Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect. plain_language: The CoA pathway contains a direct biochemical connection to the B2 cofactor FMN. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution limitations: Direct enzyme-cofactor evidence; the study did not test dietary B2 deficiency, oral riboflavin rescue, or a universal FMN threshold. FMN origin from B2 is shared nutrient context, not a newly demonstrated dietary effect. exposure: Purified human recombinant protein spectroscopy and cofactor characterization. cross_nutrient: true [b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_span

{"source_cache": "artifacts/dim-research/19884324.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214", "start_char": 0, "end_char": 1738, "text_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214"}

experimental_model

Recombinant protein and engineered bacterial coexpression

exposure

POR mutation and added FMN

limitations

In-vitro rescue of one mutant; not a dietary-riboflavin deficiency experiment or evidence that FMN reverses a DIM-drug interaction.

nutrient_topic

Diindolylmethane (DIM) research collection; topical membership is not evidence of a direct dietary effect. · 3,3'-Diindolylmethane / DIM

organism

Human POR Y181D and human CYP1A2 in engineered systems

plain_language

Inducing an enzyme is not enough if its electron-supply machinery fails.

primary_references

[dim-p19884324] Human cytochrome P450 oxidoreductase deficiency caused by the Y181D mutation: molecular consequences and rescue of defect. (2010). https://pubmed.ncbi.nlm.nih.gov/19884324/ DOI: 10.1124/dmd.109.030445

tissue_or_cell_type

FMN-dependent electron transfer

trigger_kind

machinery_impairment Imported condition classification; unverified.

Diindolylmethane (DIM): formation, receptor signaling, metabolism and drug interactions (2026-09-17) · lines 272–283

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant protein and engineered bacterial coexpression · source_derived_draft · unverified_draft

### dim-por-fmn-loss POR Y181D lacked bound FMN and poorly supported CYP1A2-catalyzed reactions despite retaining FAD binding and NADPH utilization. Condition category: machinery_impairment nutrient_topic: Diindolylmethane (DIM) research collection; topical membership is not evidence of a direct dietary effect. plain_language: Inducing an enzyme is not enough if its electron-supply machinery fails. organism: Human POR Y181D and human CYP1A2 in engineered systems tissue_or_cell_type: FMN-dependent electron transfer experimental_model: Recombinant protein and engineered bacterial coexpression limitations: In-vitro rescue of one mutant; not a dietary-riboflavin deficiency experiment or evidence that FMN reverses a DIM-drug interaction. exposure: POR mutation and added FMN evidence_span: {"source_cache": "artifacts/dim-research/19884324.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214", "start_char": 0, "end_char": 1738, "text_sha256": "3f702cc9af1528241d8572b8bcafc23dacb5ed3cacf6bb77403e8aa40d21a214"} [dim-p19884324] Human cytochrome P450 oxidoreductase deficiency caused by the Y181D mutation: molecular consequences and rescue of defect. (2010). https://pubmed.ncbi.nlm.nih.gov/19884324/ DOI: 10.1124/dmd.109.030445

cross_nutrient

true

evidence_location

Primary Figure 2C; Methods 2.3 and reconstitution assays.

experimental_model

Purified enzyme and phospholipid-vesicle reconstitution

exposure

0.25 micromolar CYP2R1; varied POR; 30 min at 37 C; Figure 2C.

limitations

Assay optimum is not a tissue expression target or a vitamin dosing requirement.

nutrient

Vitamin D2 and D3 · Vitamin D2 and D3

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens proteins

plain_language

CYP2R1 needs an electron-supplying partner.

primary_references

[cheng2018] Properties of purified CYP2R1 in a reconstituted membrane environment and its 25-hydroxylation of 20-hydroxyvitamin D3. (2018). https://pubmed.ncbi.nlm.nih.gov/28716760/ DOI: 10.1016/j.jsbmb.2017.07.011

tissue_or_cell_type

reconstituted membrane

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 392–405

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified enzyme and phospholipid-vesicle reconstitution · source_derived_draft · unverified_draft

### vd-act-por-support Human POR supported CYP2R1-mediated cholecalciferol 25-hydroxylation, with maximal measured activity near a 4:1 POR:CYP2R1 molar ratio. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: CYP2R1 needs an electron-supplying partner. organism: Homo sapiens proteins tissue_or_cell_type: reconstituted membrane experimental_model: Purified enzyme and phospholipid-vesicle reconstitution limitations: Assay optimum is not a tissue expression target or a vitamin dosing requirement. exposure: 0.25 micromolar CYP2R1; varied POR; 30 min at 37 C; Figure 2C. cross_nutrient: true evidence_location: Primary Figure 2C; Methods 2.3 and reconstitution assays. nutrient: Vitamin D2 and D3 [cheng2018] Properties of purified CYP2R1 in a reconstituted membrane environment and its 25-hydroxylation of 20-hydroxyvitamin D3. (2018). https://pubmed.ncbi.nlm.nih.gov/28716760/ DOI: 10.1016/j.jsbmb.2017.07.011

cross_nutrient

B2 activation and Mg-dependent FAD synthesis provide a biochemical partner to B1-dependent complexes; direct transfer of newly made FAD to DLD was not tested.

evidence

[{"paper_key": "brizio-2006-fad", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}]

experimental_model

Recombinant human FLAD1 isoforms expressed in E. coli.

limitations

No tissue Mg threshold or combined B1/B2 deficiency experiment.

nutrient

Thiamine (vitamin B1) · Thiamine (vitamin B1)

nutrient_topic

Thiamine research collection; topical membership is not evidence of a direct dietary effect. · Thiamine (vitamin B1)

organism

Homo sapiens

plain_language

The flavin used by E3 must first be made from the riboflavin pathway. This distinct magnesium-dependent synthesis reaction should not be confused with magnesium binding to B1 enzymes.

primary_references

[brizio-2006-fad] Over-expression in Escherichia coli and characterization of two recombinant isoforms of human FAD synthetase (2006). https://pubmed.ncbi.nlm.nih.gov/16643857/ DOI: 10.1016/j.bbrc.2006.04.003

tissue_or_cell_type

Purified/expressed proteins

Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 745–757

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human FLAD1 isoforms expressed in E. coli. · source_derived_draft · unverified_draft

### b1-fad-b2-cofactor-synthesis Recombinant human FLAD1 isoforms 1 and 2 exhibited FAD synthetase activity; isoform 2 was purified, and activity required MgCl2. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: The flavin used by E3 must first be made from the riboflavin pathway. This distinct magnesium-dependent synthesis reaction should not be confused with magnesium binding to B1 enzymes. organism: Homo sapiens tissue_or_cell_type: Purified/expressed proteins experimental_model: Recombinant human FLAD1 isoforms expressed in E. coli. limitations: No tissue Mg threshold or combined B1/B2 deficiency experiment. evidence: [{"paper_key": "brizio-2006-fad", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}] cross_nutrient: B2 activation and Mg-dependent FAD synthesis provide a biochemical partner to B1-dependent complexes; direct transfer of newly made FAD to DLD was not tested. nutrient: Thiamine (vitamin B1) [brizio-2006-fad] Over-expression in Escherichia coli and characterization of two recombinant isoforms of human FAD synthetase (2006). https://pubmed.ncbi.nlm.nih.gov/16643857/ DOI: 10.1016/j.bbrc.2006.04.003

availability_state

biomarker_context Imported condition classification; unverified.

experimental_model

124 healthy older adults, mean age 69; 46 with EGRAC >=1.20 randomized equally to riboflavin or placebo.

exposure

1.6 mg/day riboflavin versus placebo for 12 weeks; HPLC plasma/red-cell vitamer measurements.

limitations

Older adults selected by EGRAC; percentages are study responses, not diagnostic thresholds or predicted individual gains.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

Blood B2 comes in several forms, and they do not all respond equally to intake.

primary_references

[b2-hustad2002] Riboflavin, flavin mononucleotide, and flavin adenine dinucleotide in human plasma and erythrocytes at baseline and after low-dose riboflavin supplementation (2002). https://pubmed.ncbi.nlm.nih.gov/12194936/ DOI: 10.1093/clinchem/48.9.1571

tissue_or_cell_type

Human clinical setting

trigger_kind

biomarker_context Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1617–1627

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 124 healthy older adults, mean age 69; 46 with EGRAC >=1.20 randomized equally to riboflavin or placebo. · source_derived_draft · unverified_draft

### b2-blood-vitamer-response In 46 randomized older adults, supplementation increased plasma riboflavin by 83% and erythrocyte FMN by 87%; measured markers other than plasma FAD responded significantly. Condition category: biomarker_context nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Blood B2 comes in several forms, and they do not all respond equally to intake. organism: Homo sapiens tissue_or_cell_type: Human clinical setting experimental_model: 124 healthy older adults, mean age 69; 46 with EGRAC >=1.20 randomized equally to riboflavin or placebo. limitations: Older adults selected by EGRAC; percentages are study responses, not diagnostic thresholds or predicted individual gains. exposure: 1.6 mg/day riboflavin versus placebo for 12 weeks; HPLC plasma/red-cell vitamer measurements. [b2-hustad2002] Riboflavin, flavin mononucleotide, and flavin adenine dinucleotide in human plasma and erythrocytes at baseline and after low-dose riboflavin supplementation (2002). https://pubmed.ncbi.nlm.nih.gov/12194936/ DOI: 10.1093/clinchem/48.9.1571

availability_state

biomarker_context Imported condition classification; unverified.

experimental_model

119 healthy controls and 125 critically ill patients at admission; repeat measurements in 60 patients.

exposure

Observational HPLC plasma and red-cell riboflavin, FMN andFAD; no isolated treatment.

limitations

Observational illness comparison cannot diagnose tissue deficiency or establish that supplementation improves outcomes.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

A high circulating B2 concentration during critical illness can coexist with a lower measured cellular FAD pool.

primary_references

[b2-ventura2010] Relation between riboflavin, flavin mononucleotide and flavin adenine dinucleotide concentrations in plasma and red cells in patients with critical illness (2010). https://pubmed.ncbi.nlm.nih.gov/20667447/ DOI: 10.1016/j.cca.2010.07.024

tissue_or_cell_type

Human clinical setting

trigger_kind

biomarker_context Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1641–1651

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 119 healthy controls and 125 critically ill patients at admission; repeat measurements in 60 patients. · source_derived_draft · unverified_draft

### b2-critical-illness-pools Critically ill patients had higher plasma riboflavin and FMN but lower plasma and red-cell FAD than healthy controls; plasma-vitamer relationships were disrupted. Condition category: biomarker_context nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: A high circulating B2 concentration during critical illness can coexist with a lower measured cellular FAD pool. organism: Homo sapiens tissue_or_cell_type: Human clinical setting experimental_model: 119 healthy controls and 125 critically ill patients at admission; repeat measurements in 60 patients. limitations: Observational illness comparison cannot diagnose tissue deficiency or establish that supplementation improves outcomes. exposure: Observational HPLC plasma and red-cell riboflavin, FMN andFAD; no isolated treatment. [b2-ventura2010] Relation between riboflavin, flavin mononucleotide and flavin adenine dinucleotide concentrations in plasma and red cells in patients with critical illness (2010). https://pubmed.ncbi.nlm.nih.gov/20667447/ DOI: 10.1016/j.cca.2010.07.024

availability_state

biomarker_context Imported condition classification; unverified.

cross_nutrient

G6PD genotype and distinct flavin pools alter interpretation of B2/B6-linked assays.

experimental_model

Human erythrocytes from G6PD deficiency, heterozygous beta-thalassemia and controls.

exposure

In-vitro FAD stimulation of glutathione reductase and PNP oxidase activity, with oral-riboflavin response observations.

limitations

Human red-cell observation; the proposed faster FMN-to-FAD flux was an interpretation, not a directly measured universal mechanism.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

A red-cell FAD saturation test can look adequate while another B2-dependent enzyme system is poorly supplied.

primary_references

[b2-anderson1987] Glutathione reductase activity and its relationship to pyridoxine phosphate activity in G6PD deficiency (1987). https://pubmed.ncbi.nlm.nih.gov/3582603/ DOI: 10.1111/j.1600-0609.1987.tb01417.x

tissue_or_cell_type

Human clinical setting

trigger_kind

biomarker_context Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1666–1677

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human erythrocytes from G6PD deficiency, heterozygous beta-thalassemia and controls. · source_derived_draft · unverified_draft

### b2-g6pd-fad-assay-limit In G6PD-deficient erythrocytes, glutathione reductase was usually already FAD-saturated despite evidence of low FMN-dependent oxidase activity. Condition category: biomarker_context nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: A red-cell FAD saturation test can look adequate while another B2-dependent enzyme system is poorly supplied. organism: Homo sapiens tissue_or_cell_type: Human clinical setting experimental_model: Human erythrocytes from G6PD deficiency, heterozygous beta-thalassemia and controls. limitations: Human red-cell observation; the proposed faster FMN-to-FAD flux was an interpretation, not a directly measured universal mechanism. exposure: In-vitro FAD stimulation of glutathione reductase and PNP oxidase activity, with oral-riboflavin response observations. cross_nutrient: G6PD genotype and distinct flavin pools alter interpretation of B2/B6-linked assays. [b2-anderson1987] Glutathione reductase activity and its relationship to pyridoxine phosphate activity in G6PD deficiency (1987). https://pubmed.ncbi.nlm.nih.gov/3582603/ DOI: 10.1111/j.1600-0609.1987.tb01417.x

availability_state

biomarker_context Imported condition classification; unverified.

cross_nutrient

B2 cofactor supply affects a B6-activation assay.

experimental_model

Human erythrocytes from G6PD deficiency, heterozygous beta-thalassemia and controls.

exposure

In-vitro FAD stimulation of glutathione reductase and PNP oxidase activity, with oral-riboflavin response observations.

limitations

No isolated whole-body B6 flux or clinical seizure/neuropathy outcome was established.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

FMN and FAD should not be treated as one interchangeable vitamin pool.

primary_references

[b2-anderson1987] Glutathione reductase activity and its relationship to pyridoxine phosphate activity in G6PD deficiency (1987). https://pubmed.ncbi.nlm.nih.gov/3582603/ DOI: 10.1111/j.1600-0609.1987.tb01417.x

tissue_or_cell_type

Human clinical setting

trigger_kind

biomarker_context Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1679–1690

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human erythrocytes from G6PD deficiency, heterozygous beta-thalassemia and controls. · source_derived_draft · unverified_draft

### b2-g6pd-fmn-oxidase-response Low FMN-dependent PNP oxidase activity in many G6PD-deficient participants responded to oral riboflavin despite the contrasting FAD-saturated GSR pattern. Condition category: biomarker_context nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: FMN and FAD should not be treated as one interchangeable vitamin pool. organism: Homo sapiens tissue_or_cell_type: Human clinical setting experimental_model: Human erythrocytes from G6PD deficiency, heterozygous beta-thalassemia and controls. limitations: No isolated whole-body B6 flux or clinical seizure/neuropathy outcome was established. exposure: In-vitro FAD stimulation of glutathione reductase and PNP oxidase activity, with oral-riboflavin response observations. cross_nutrient: B2 cofactor supply affects a B6-activation assay. [b2-anderson1987] Glutathione reductase activity and its relationship to pyridoxine phosphate activity in G6PD deficiency (1987). https://pubmed.ncbi.nlm.nih.gov/3582603/ DOI: 10.1111/j.1600-0609.1987.tb01417.x

availability_state

nutrient_deficiency Imported condition classification; unverified.

evidence_spans

[{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC7477094", "locator": "XML .//body//p", "paragraph_index": 21, "char_start": 0, "char_end": 3026, "evidence_access": "full-text"}]

experimental_model

Mouse B16 melanoma cells cultured in riboflavin-free medium for 3 days; quantitative proteomics.

exposure

Riboflavin-free culture for three days; quantitative proteomics.

limitations

Abundance, not direct pathway flux; cancer-cell dependence may differ from normal cells.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Mus musculus

plain_language

Removing B2 lowered the abundance of respiratory machinery in these tumor cells.

primary_references

[martinez-limon-2020-b2-depletion] Flavin dependency undermines proteome stability, lipid metabolism and cellular proliferation during vitamin B2 deficiency (2020). https://pubmed.ncbi.nlm.nih.gov/32895367/ DOI: 10.1038/s41419-020-02929-5

tissue_or_cell_type

B16 melanoma cells

trigger_kind

nutrient_deficiency Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 970–981

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Mouse B16 melanoma cells cultured in riboflavin-free medium for 3 days; quantitative proteomics. · source_derived_draft · unverified_draft

### b2-met-b16-respiratory-proteome Three-day riboflavin starvation of mouse B16 cells reduced proteomic clusters associated with electron transport and ATP synthesis. Condition category: nutrient_deficiency nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Removing B2 lowered the abundance of respiratory machinery in these tumor cells. organism: Mus musculus tissue_or_cell_type: B16 melanoma cells experimental_model: Mouse B16 melanoma cells cultured in riboflavin-free medium for 3 days; quantitative proteomics. limitations: Abundance, not direct pathway flux; cancer-cell dependence may differ from normal cells. exposure: Riboflavin-free culture for three days; quantitative proteomics. evidence_spans: [{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC7477094", "locator": "XML .//body//p", "paragraph_index": 21, "char_start": 0, "char_end": 3026, "evidence_access": "full-text"}] [martinez-limon-2020-b2-depletion] Flavin dependency undermines proteome stability, lipid metabolism and cellular proliferation during vitamin B2 deficiency (2020). https://pubmed.ncbi.nlm.nih.gov/32895367/ DOI: 10.1038/s41419-020-02929-5

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_spans

[{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC2440658", "locator": "HTML article p", "paragraph_index": 11, "char_start": 0, "char_end": 1107, "evidence_access": "full-text"}]

experimental_model

Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution.

exposure

10 micromolar riboflavin, FAD or FMN in the reconstitution comparison.

limitations

Does not test intact-cell conversion of riboflavin into FMN.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Bos taurus

plain_language

Free B2 and FAD could not substitute directly for FMN in this test tube.

primary_references

[gostimskaya-2007-complex-i-fmn] Reversible dissociation of flavin mononucleotide from the mammalian membrane-bound NADH: ubiquinone oxidoreductase (complex I) (2007). https://pubmed.ncbi.nlm.nih.gov/18037377/ DOI: 10.1016/j.febslet.2007.11.048

tissue_or_cell_type

Heart submitochondrial particles

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 596–607

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution. · source_derived_draft · unverified_draft

### b2-met-complex-i-flavin-specificity Riboflavin and FAD failed to protect or reactivate alkaline-inactivated bovine complex I under conditions where FMN did. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Free B2 and FAD could not substitute directly for FMN in this test tube. organism: Bos taurus tissue_or_cell_type: Heart submitochondrial particles experimental_model: Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution. limitations: Does not test intact-cell conversion of riboflavin into FMN. exposure: 10 micromolar riboflavin, FAD or FMN in the reconstitution comparison. evidence_spans: [{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC2440658", "locator": "HTML article p", "paragraph_index": 11, "char_start": 0, "char_end": 1107, "evidence_access": "full-text"}] [gostimskaya-2007-complex-i-fmn] Reversible dissociation of flavin mononucleotide from the mammalian membrane-bound NADH: ubiquinone oxidoreductase (complex I) (2007). https://pubmed.ncbi.nlm.nih.gov/18037377/ DOI: 10.1016/j.febslet.2007.11.048

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_spans

[{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC2440658", "locator": "HTML article p", "paragraph_index": 11, "char_start": 0, "char_end": 1107, "evidence_access": "full-text"}]

experimental_model

Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution.

exposure

NADH with rotenone or cyanide, alkaline pH; time-dependent NADH:HAR and NADH:Q1 assays.

limitations

Biochemical inference from kinetic/cofactor reconstitution experiments; nonphysiological pH.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Bos taurus

plain_language

An unusually reduced, alkaline laboratory environment loosened the enzyme-bound flavin.

primary_references

[gostimskaya-2007-complex-i-fmn] Reversible dissociation of flavin mononucleotide from the mammalian membrane-bound NADH: ubiquinone oxidoreductase (complex I) (2007). https://pubmed.ncbi.nlm.nih.gov/18037377/ DOI: 10.1016/j.febslet.2007.11.048

tissue_or_cell_type

Heart submitochondrial particles

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 583–594

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution. · source_derived_draft · unverified_draft

### b2-met-complex-i-reductive-fmn-loss NADH plus respiratory blockade at alkaline pH caused time-dependent activity loss consistent with reversible FMN dissociation from bovine membrane-bound complex I. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: An unusually reduced, alkaline laboratory environment loosened the enzyme-bound flavin. organism: Bos taurus tissue_or_cell_type: Heart submitochondrial particles experimental_model: Bovine heart submitochondrial particles; alkaline reductive inactivation and cofactor reconstitution. limitations: Biochemical inference from kinetic/cofactor reconstitution experiments; nonphysiological pH. exposure: NADH with rotenone or cyanide, alkaline pH; time-dependent NADH:HAR and NADH:Q1 assays. evidence_spans: [{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC2440658", "locator": "HTML article p", "paragraph_index": 11, "char_start": 0, "char_end": 1107, "evidence_access": "full-text"}] [gostimskaya-2007-complex-i-fmn] Reversible dissociation of flavin mononucleotide from the mammalian membrane-bound NADH: ubiquinone oxidoreductase (complex I) (2007). https://pubmed.ncbi.nlm.nih.gov/18037377/ DOI: 10.1016/j.febslet.2007.11.048

availability_state

nutrient_deficiency Imported condition classification; unverified.

evidence_spans

[{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10767280", "locator": "XML .//body//p", "paragraph_index": 58, "char_start": 0, "char_end": 905, "evidence_access": "full-text"}]

experimental_model

Human 143B cells and mouse adult fibroblasts, riboflavin-free medium and separate DPI interventions.

exposure

Riboflavin-free medium; matched control contained 1 micromolar riboflavin.

limitations

Cell-culture withdrawal; proteomic abundance does not establish a human blood threshold.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens; Mus musculus

plain_language

Removing B2 reduced parts needed to build the respiratory enzyme.

primary_references

[curtabbi-2024-fmn-assembly] Regulation of respiratory complex I assembly by FMN cofactor targeting (2024). https://pubmed.ncbi.nlm.nih.gov/38145589/ DOI: 10.1016/j.redox.2023.103001

tissue_or_cell_type

143B cells and mouse adult fibroblasts

trigger_kind

nutrient_deficiency Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 609–620

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human 143B cells and mouse adult fibroblasts, riboflavin-free medium and separate DPI interventions. · source_derived_draft · unverified_draft

### b2-met-depletion-complex-i Riboflavin-free culture reduced complex I abundance; human 143B proteomics identified particularly strong loss of its NADH-oxidizing N-module subunits. Condition category: nutrient_deficiency nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Removing B2 reduced parts needed to build the respiratory enzyme. organism: Homo sapiens; Mus musculus tissue_or_cell_type: 143B cells and mouse adult fibroblasts experimental_model: Human 143B cells and mouse adult fibroblasts, riboflavin-free medium and separate DPI interventions. limitations: Cell-culture withdrawal; proteomic abundance does not establish a human blood threshold. exposure: Riboflavin-free medium; matched control contained 1 micromolar riboflavin. evidence_spans: [{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10767280", "locator": "XML .//body//p", "paragraph_index": 58, "char_start": 0, "char_end": 905, "evidence_access": "full-text"}] [curtabbi-2024-fmn-assembly] Regulation of respiratory complex I assembly by FMN cofactor targeting (2024). https://pubmed.ncbi.nlm.nih.gov/38145589/ DOI: 10.1016/j.redox.2023.103001

cross_nutrient

B2-derived flavins form part of the B12-reactivation machinery.

evidence_location

Abstract

experimental_model

Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution.

exposure

Purified-enzyme assay

limitations

Biochemical evidence does not establish a dietary threshold or supplementation benefit.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

MTRR uses both B2-derived cofactors.

primary_references

[olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. (2001). https://pubmed.ncbi.nlm.nih.gov/11466310/ DOI: 10.1074/jbc.m103707200

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1094–1106

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution. · source_derived_draft · unverified_draft

### b2-mtrr-dual-flavins Purified recombinant human MTRR contained equimolar FAD and FMN, identifying two distinct flavin cofactors in the same reductase. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: MTRR uses both B2-derived cofactors. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution. limitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit. exposure: Purified-enzyme assay cross_nutrient: B2-derived flavins form part of the B12-reactivation machinery. evidence_location: Abstract [olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. (2001). https://pubmed.ncbi.nlm.nih.gov/11466310/ DOI: 10.1074/jbc.m103707200

cross_nutrient

B2 flavins support reactivation of B12-dependent folate/homocysteine metabolism.

evidence_location

Abstract

experimental_model

Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution.

exposure

Purified-enzyme assay

limitations

Reconstituted biochemistry; the accessible abstract identifies human MTRR but not the target MTR species. No dietary B2/B12 synergy was tested.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

The flavin reductase helps restore an enzyme that uses B12 and methylfolate.

primary_references

[olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. (2001). https://pubmed.ncbi.nlm.nih.gov/11466310/ DOI: 10.1074/jbc.m103707200

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1122–1134

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution. · source_derived_draft · unverified_draft

### b2-mtrr-mtr-reactivation Reconstituted assays showed human MTRR sufficient to support NADPH-dependent activity of cobalamin-dependent methionine synthase. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The flavin reductase helps restore an enzyme that uses B12 and methylfolate. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution. limitations: Reconstituted biochemistry; the accessible abstract identifies human MTRR but not the target MTR species. No dietary B2/B12 synergy was tested. exposure: Purified-enzyme assay cross_nutrient: B2 flavins support reactivation of B12-dependent folate/homocysteine metabolism. evidence_location: Abstract [olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. (2001). https://pubmed.ncbi.nlm.nih.gov/11466310/ DOI: 10.1074/jbc.m103707200

cross_nutrient

Nicotinamide-containing NADPH supplies electrons to B2-derived flavins.

evidence_location

Abstract

experimental_model

Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution.

exposure

Purified-enzyme assay

limitations

Biochemical evidence does not establish a dietary threshold or supplementation benefit.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

NADPH provides electrons to the flavin-containing reductase.

primary_references

[olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. (2001). https://pubmed.ncbi.nlm.nih.gov/11466310/ DOI: 10.1074/jbc.m103707200

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1108–1120

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution. · source_derived_draft · unverified_draft

### b2-mtrr-nadph-reduction NADPH reduction of purified MTRR generated an air-stable flavin semiquinone detected spectroscopically. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: NADPH provides electrons to the flavin-containing reductase. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution. limitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit. exposure: Purified-enzyme assay cross_nutrient: Nicotinamide-containing NADPH supplies electrons to B2-derived flavins. evidence_location: Abstract [olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. (2001). https://pubmed.ncbi.nlm.nih.gov/11466310/ DOI: 10.1074/jbc.m103707200

cross_nutrient

A second B6 precursor depends on the FMN enzyme.

evidence_location

Results: kinetic properties; Table 1; FMN-binding structure

experimental_model

Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C.

exposure

Purified-enzyme assay

limitations

Biochemical evidence does not establish a dietary threshold or supplementation benefit.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

Phosphorylated pyridoxamine enters the same activation enzyme.

primary_references

[musayev2003] Structure and properties of recombinant human pyridoxine 5'-phosphate oxidase. (2003). https://pubmed.ncbi.nlm.nih.gov/12824491/ DOI: 10.1110/ps.0356203

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1164–1176

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C. · source_derived_draft · unverified_draft

### b2-pnpo-pmp-oxidation Human PNPO also converted PMP to PLP, with a turnover number of 0.20 per second at 37 C. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Phosphorylated pyridoxamine enters the same activation enzyme. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C. limitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit. exposure: Purified-enzyme assay cross_nutrient: A second B6 precursor depends on the FMN enzyme. evidence_location: Results: kinetic properties; Table 1; FMN-binding structure [musayev2003] Structure and properties of recombinant human pyridoxine 5'-phosphate oxidase. (2003). https://pubmed.ncbi.nlm.nih.gov/12824491/ DOI: 10.1110/ps.0356203

cross_nutrient

B2-dependent oxidation activates one B6 precursor.

evidence_location

Results: kinetic properties; Table 1; FMN-binding structure

experimental_model

Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C.

exposure

Purified-enzyme assay

limitations

Biochemical evidence does not establish a dietary threshold or supplementation benefit.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

PNPO changes phosphorylated pyridoxine into active B6.

primary_references

[musayev2003] Structure and properties of recombinant human pyridoxine 5'-phosphate oxidase. (2003). https://pubmed.ncbi.nlm.nih.gov/12824491/ DOI: 10.1110/ps.0356203

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1150–1162

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C. · source_derived_draft · unverified_draft

### b2-pnpo-pnp-oxidation Purified human PNPO converted PNP to PLP with a turnover number of 0.19 per second at 37 C. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: PNPO changes phosphorylated pyridoxine into active B6. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human PNPO expressed in E. coli; crystallography and purified-enzyme kinetics at 37 C. limitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit. exposure: Purified-enzyme assay cross_nutrient: B2-dependent oxidation activates one B6 precursor. evidence_location: Results: kinetic properties; Table 1; FMN-binding structure [musayev2003] Structure and properties of recombinant human pyridoxine 5'-phosphate oxidase. (2003). https://pubmed.ncbi.nlm.nih.gov/12824491/ DOI: 10.1110/ps.0356203

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

B2-cofactor binding is one part of a broader genetic defect in B6 activation.

evidence_location

Results: Table 3 and Fig 1; Table 2 and Fig 2

experimental_model

Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure.

exposure

Purified-enzyme assay

limitations

Km is a kinetic parameter, not a direct binding constant; adding FMN alone was not shown to normalize this whole defect.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

The defect also changes substrate handling and reaction speed.

primary_references

[musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372

tissue_or_cell_type

Purified recombinant enzyme; no intact tissue

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1220–1232

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. · source_derived_draft · unverified_draft

### b2-pnpo-r229w-catalytic-efficiency R229W PNPO showed approximately 850-fold lower PNP catalytic efficiency, combining a 192-fold higher Km and 4.5-fold lower kcat. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The defect also changes substrate handling and reaction speed. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. limitations: Km is a kinetic parameter, not a direct binding constant; adding FMN alone was not shown to normalize this whole defect. exposure: Purified-enzyme assay cross_nutrient: B2-cofactor binding is one part of a broader genetic defect in B6 activation. evidence_location: Results: Table 3 and Fig 1; Table 2 and Fig 2 [musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372

availability_state

biomarker_context Imported condition classification; unverified.

cross_nutrient

A B6-activation enzyme provides a B2-sensitive functional assay.

experimental_model

Assay-development study using hemolysates from the RIBOFEM riboflavin intervention; same trial registration ISRCTN35811298.

exposure

Erythrocyte PPO activity with/without flavin activation; 2 and 4 mg/day supplementation arms. Not independent replication of RIBOFEM.

limitations

Assay-development analysis shares samples with RIBOFEM; not independent replication. Proposed utility in G6PD deficiency requires population-specific validation.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

An enzyme used to activate B6 can also reveal aspects of B2 status because it needs an FMN cofactor.

primary_references

[b2-mushtaq2009] Erythrocyte pyridoxamine phosphate oxidase activity: a potential biomarker of riboflavin status? (2009). https://pubmed.ncbi.nlm.nih.gov/19740970/ DOI: 10.3945/ajcn.2009.28338

tissue_or_cell_type

Human clinical setting

trigger_kind

biomarker_context Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1653–1664

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Assay-development study using hemolysates from the RIBOFEM riboflavin intervention; same trial registration ISRCTN35811298. · source_derived_draft · unverified_draft

### b2-ppo-biomarker-response Erythrocyte PPO activity and its activation coefficient responded to B2 supplementation and correlated with EGRAC; enzyme activity showed a dose response. Condition category: biomarker_context nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: An enzyme used to activate B6 can also reveal aspects of B2 status because it needs an FMN cofactor. organism: Homo sapiens tissue_or_cell_type: Human clinical setting experimental_model: Assay-development study using hemolysates from the RIBOFEM riboflavin intervention; same trial registration ISRCTN35811298. limitations: Assay-development analysis shares samples with RIBOFEM; not independent replication. Proposed utility in G6PD deficiency requires population-specific validation. exposure: Erythrocyte PPO activity with/without flavin activation; 2 and 4 mg/day supplementation arms. Not independent replication of RIBOFEM. cross_nutrient: A B6-activation enzyme provides a B2-sensitive functional assay. [b2-mushtaq2009] Erythrocyte pyridoxamine phosphate oxidase activity: a potential biomarker of riboflavin status? (2009). https://pubmed.ncbi.nlm.nih.gov/19740970/ DOI: 10.3945/ajcn.2009.28338

cross_nutrient

Magnesium is a cofactor for a vitamin B2 activation step.

evidence_location

Abstract and activity assay

experimental_model

Recombinant human FADS2 expressed in E. coli and purified

exposure

MgCl2 requirement tested in purified enzyme assays.

limitations

Assay-specific metal dependence does not quantify human dietary magnesium effects on flavins.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens protein

plain_language

Magnesium supports enzymatic conversion of FMN into FAD.

primary_references

[transport-fads2-2007] Over-expression in Escherichia coli, purification and characterization of isoform 2 of human FAD synthetase. (2007). https://doi.org/10.1016/j.pep.2006.09.002 DOI: 10.1016/j.pep.2006.09.002

tissue_or_cell_type

Purified enzyme

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 333–345

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human FADS2 expressed in E. coli and purified · source_derived_draft · unverified_draft

### transport-flad1-magnesium-requirement Purified human FADS2 showed a strict MgCl2 requirement in the reported spectrophotometric FAD-synthesis assay. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium supports enzymatic conversion of FMN into FAD. organism: Homo sapiens protein tissue_or_cell_type: Purified enzyme experimental_model: Recombinant human FADS2 expressed in E. coli and purified limitations: Assay-specific metal dependence does not quantify human dietary magnesium effects on flavins. exposure: MgCl2 requirement tested in purified enzyme assays. cross_nutrient: Magnesium is a cofactor for a vitamin B2 activation step. evidence_location: Abstract and activity assay [transport-fads2-2007] Over-expression in Escherichia coli, purification and characterization of isoform 2 of human FAD synthetase. (2007). https://doi.org/10.1016/j.pep.2006.09.002 DOI: 10.1016/j.pep.2006.09.002

cross_nutrient

Magnesium supports the chemistry used to activate vitamin B2; no blood-magnesium threshold is established.

evidence_location

Abstract; metal-coordination structural analysis

experimental_model

Product-bound human RFK crystallography

exposure

Co-crystallization with MgADP and FMN.

limitations

A metal-bound enzyme structure is not a clinical magnesium-deficiency or supplementation experiment.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

Magnesium participates directly in the RFK active site.

primary_references

[transport-rfk-2003] Ligand binding-induced conformational changes in riboflavin kinase: structural basis for the ordered mechanism. (2003). https://pubmed.ncbi.nlm.nih.gov/14580199/ DOI: 10.1021/bi035450t

tissue_or_cell_type

Purified protein

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 306–318

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Product-bound human RFK crystallography · source_derived_draft · unverified_draft

### transport-rfk-magnesium-coordination Human RFK crystallized with MgADP and FMN showed magnesium coordination by an FMN phosphate oxygen and Asn36. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium participates directly in the RFK active site. organism: Homo sapiens tissue_or_cell_type: Purified protein experimental_model: Product-bound human RFK crystallography limitations: A metal-bound enzyme structure is not a clinical magnesium-deficiency or supplementation experiment. exposure: Co-crystallization with MgADP and FMN. cross_nutrient: Magnesium supports the chemistry used to activate vitamin B2; no blood-magnesium threshold is established. evidence_location: Abstract; metal-coordination structural analysis [transport-rfk-2003] Ligand binding-induced conformational changes in riboflavin kinase: structural basis for the ordered mechanism. (2003). https://pubmed.ncbi.nlm.nih.gov/14580199/ DOI: 10.1021/bi035450t

evidence_location

Abstract and product-bound structure

experimental_model

Human RFK structural and catalytic mechanism study

exposure

Purified RFK with flavin and adenine nucleotide ligands.

limitations

Reaction chemistry does not imply RFK controls every tissue flavin pool to the same extent.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

RFK performs the first activation step from riboflavin to FMN.

primary_references

[transport-rfk-2003] Ligand binding-induced conformational changes in riboflavin kinase: structural basis for the ordered mechanism. (2003). https://pubmed.ncbi.nlm.nih.gov/14580199/ DOI: 10.1021/bi035450t

tissue_or_cell_type

Purified protein

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 293–304

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human RFK structural and catalytic mechanism study · source_derived_draft · unverified_draft

### transport-rfk-phosphorylation Human RFK phosphorylates riboflavin to FMN using ATP, yielding ADP; this precedes FLAD1-mediated FAD synthesis. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: RFK performs the first activation step from riboflavin to FMN. organism: Homo sapiens tissue_or_cell_type: Purified protein experimental_model: Human RFK structural and catalytic mechanism study limitations: Reaction chemistry does not imply RFK controls every tissue flavin pool to the same extent. exposure: Purified RFK with flavin and adenine nucleotide ligands. evidence_location: Abstract and product-bound structure [transport-rfk-2003] Ligand binding-induced conformational changes in riboflavin kinase: structural basis for the ordered mechanism. (2003). https://pubmed.ncbi.nlm.nih.gov/14580199/ DOI: 10.1021/bi035450t

evidence_location

Figure 3C-E

experimental_model

HEK293 expression; HPLC measurement of flavin uptake

exposure

10 micromolar flavin, pH 7.4, 10 minutes, 37 C.

limitations

Substrate preference under these conditions is not proof of zero FMN transport at every concentration.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

Free riboflavin was the preferred transported flavin.

primary_references

[transport-rfvt3-2014] Functional involvement of RFVT3/SLC52A3 in intestinal riboflavin absorption. (2014). https://doi.org/10.1152/ajpgi.00349.2013 DOI: 10.1152/ajpgi.00349.2013

tissue_or_cell_type

HEK293 cells

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 228–239

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · HEK293 expression; HPLC measurement of flavin uptake · source_derived_draft · unverified_draft

### transport-rfvt3-substrate-discrimination RFVT3-expressing HEK293 cells transported riboflavin strongly, FMN weakly, and showed no measurable FAD transport in the reported assay. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Free riboflavin was the preferred transported flavin. organism: Homo sapiens tissue_or_cell_type: HEK293 cells experimental_model: HEK293 expression; HPLC measurement of flavin uptake limitations: Substrate preference under these conditions is not proof of zero FMN transport at every concentration. exposure: 10 micromolar flavin, pH 7.4, 10 minutes, 37 C. evidence_location: Figure 3C-E [transport-rfvt3-2014] Functional involvement of RFVT3/SLC52A3 in intestinal riboflavin absorption. (2014). https://doi.org/10.1152/ajpgi.00349.2013 DOI: 10.1152/ajpgi.00349.2013

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_location

Table 3 and Methods/results

experimental_model

Single genetic case; plasma flavin assay

exposure

Pretreatment plasma measurements.

limitations

One case; normal plasma measurements are not direct measurements of neuronal flavin sufficiency.

nutrient_topic

Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)

organism

Homo sapiens

plain_language

Normal plasma flavins did not exclude a cellular transport defect.

primary_references

[transport-slc52a2-disease-2012] Impaired riboflavin transport due to missense mutations in SLC52A2 causes Brown-Vialetto-Van Laere syndrome (2012). https://pmc.ncbi.nlm.nih.gov/articles/PMC3470687/ DOI: 10.1007/s10545-012-9513-y

tissue_or_cell_type

Plasma and clinical nervous-system phenotype

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 451–462

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Single genetic case; plasma flavin assay · source_derived_draft · unverified_draft

### transport-slc52a2-normal-plasma The child with compound SLC52A2 L123P/L339P variants had normal measured plasma riboflavin, FMN and FAD despite a transport-associated neurologic disorder. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Normal plasma flavins did not exclude a cellular transport defect. organism: Homo sapiens tissue_or_cell_type: Plasma and clinical nervous-system phenotype experimental_model: Single genetic case; plasma flavin assay limitations: One case; normal plasma measurements are not direct measurements of neuronal flavin sufficiency. exposure: Pretreatment plasma measurements. evidence_location: Table 3 and Methods/results [transport-slc52a2-disease-2012] Impaired riboflavin transport due to missense mutations in SLC52A2 causes Brown-Vialetto-Van Laere syndrome (2012). https://pmc.ncbi.nlm.nih.gov/articles/PMC3470687/ DOI: 10.1007/s10545-012-9513-y

evidence_access

Primary abstract

experimental_model

Acinetobacter enzyme redox spectroscopy and site-directed mutants.

limitations

Bacterial cofactor dependence does not show that human B2 or iron supplementation increases TMAO.

nutrient_topic

L-Carnitine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnitine

plain_language

Riboflavin-derived FMN, iron centers and NADH connect to microbial carnitine chemistry.

primary_references

Carnitine metabolism in the human gut: characterization of the two-component carnitine monooxygenase CntAB from Acinetobacter baumannii. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32694223/ · DOI 10.1074/jbc.RA120.014266

L-Carnitine: synthesis, acyl-group transport, fuel selection and nutrient interactions (2026-09-19) · lines 394–400

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Acinetobacter enzyme redox spectroscopy and site-directed mutants. · source_derived_draft · unverified_draft

## l-carnitine-cntb-redox Riboflavin-derived FMN, iron centers and NADH connect to microbial carnitine chemistry. CntB passed NADH-derived electrons through FMN and iron-sulfur centers to support CntA oxygen activation. Model: Acinetobacter enzyme redox spectroscopy and site-directed mutants. Limitations: Bacterial cofactor dependence does not show that human B2 or iron supplementation increases TMAO. Evidence access: Primary abstract Carnitine metabolism in the human gut: characterization of the two-component carnitine monooxygenase CntAB from Acinetobacter baumannii. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32694223/ · DOI 10.1074/jbc.RA120.014266

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

true

evidence_location

Experimental procedures and Results: CblC Has a Flavin Reductase Fold; Figure 1c

experimental_model

Recombinant human MMACHC deltaC38 biochemical assay

exposure

30–40 micromolar FMN/FAD with 200 micromolar NADPH, or photoreduced FMN

limitations

Engineered truncation and reconstitution; does not establish that riboflavin supplementation rescues MMACHC defects.

nutrient_topic

Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)

organism

Homo sapiens

plain_language

A truncated B12-processing protein could use supplied flavins to carry out this reaction.

primary_references

[koutmos-2011-flavin] Structural Basis of Multifunctionality in a Vitamin B12-processing Enzyme (2011). https://pubmed.ncbi.nlm.nih.gov/21697092/ DOI: 10.1074/jbc.M111.261370

tissue_or_cell_type

Cell-free assay

trigger_kind

machinery_impairment Imported condition classification; unverified.

Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 753–765

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human MMACHC deltaC38 biochemical assay · source_derived_draft · unverified_draft

### b12-mmachc-free-flavin-decyanation Human MMACHC residues 1–244 supported cyanocobalamin decyanation with FMN or FAD plus NADPH, without a separately supplied flavoprotein reductase; reduced FMN also supported the reaction. Condition category: machinery_impairment nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A truncated B12-processing protein could use supplied flavins to carry out this reaction. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Recombinant human MMACHC deltaC38 biochemical assay limitations: Engineered truncation and reconstitution; does not establish that riboflavin supplementation rescues MMACHC defects. exposure: 30–40 micromolar FMN/FAD with 200 micromolar NADPH, or photoreduced FMN cross_nutrient: true evidence_location: Experimental procedures and Results: CblC Has a Flavin Reductase Fold; Figure 1c [koutmos-2011-flavin] Structural Basis of Multifunctionality in a Vitamin B12-processing Enzyme (2011). https://pubmed.ncbi.nlm.nih.gov/21697092/ DOI: 10.1074/jbc.M111.261370

cross_nutrient

true

evidence_location

Results: Figure 4; Materials and Methods: Decyanation of CNCbl

experimental_model

Human purified-protein anaerobic reconstitution

exposure

4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH

limitations

Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans.

nutrient_topic

Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)

organism

Homo sapiens

plain_language

This flavoprotein can pass reducing power into B12 processing.

primary_references

[kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105

tissue_or_cell_type

Cell-free assay

Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 683–695

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human purified-protein anaerobic reconstitution · source_derived_draft · unverified_draft

### b12-mtrr-mmachc-electrons Recombinant human MTRR with NADPH supported MMACHC-bound cyanocobalamin conversion to cob(II)alamin; free cyanocobalamin was not detectably reduced without MMACHC. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This flavoprotein can pass reducing power into B12 processing. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Human purified-protein anaerobic reconstitution limitations: Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans. exposure: 4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH cross_nutrient: true evidence_location: Results: Figure 4; Materials and Methods: Decyanation of CNCbl [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105

cross_nutrient

true

evidence_location

Results: Figure 4; Materials and Methods: Decyanation of CNCbl

experimental_model

Human purified-protein anaerobic reconstitution

exposure

4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH

limitations

Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans.

nutrient_topic

Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)

organism

Homo sapiens

plain_language

This flavoprotein can pass reducing power into B12 processing.

primary_references

[kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105

tissue_or_cell_type

Cell-free assay

Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 697–709

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human purified-protein anaerobic reconstitution · source_derived_draft · unverified_draft

### b12-ndor1-mmachc-electrons Recombinant human NDOR1/NR1 with NADPH supported MMACHC-bound cyanocobalamin conversion to cob(II)alamin; free cyanocobalamin was not detectably reduced without MMACHC. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This flavoprotein can pass reducing power into B12 processing. organism: Homo sapiens tissue_or_cell_type: Cell-free assay experimental_model: Human purified-protein anaerobic reconstitution limitations: Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans. exposure: 4 micromolar reductase, 20 micromolar MMACHC/CNCbl, 200 micromolar NADPH cross_nutrient: true evidence_location: Results: Figure 4; Materials and Methods: Decyanation of CNCbl [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105

cross_nutrient

true

evidence_location

Indexed primary abstract

experimental_model

Purified human proteins

exposure

Purified MTRR plus MMAB and reductants

limitations

MTRR coupling in vitro does not identify the physiological mitochondrial electron donor.

nutrient_topic

Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)

organism

Homo sapiens

plain_language

Human MTRR supported B12 activation in a test-tube system; this does not establish its mitochondrial role.

primary_references

[leal-2004-human-mmab] Human ATP:Cob(I)alamin adenosyltransferase and its interaction with methionine synthase reductase. (2004). https://pubmed.ncbi.nlm.nih.gov/15347655/ DOI: 10.1074/jbc.m405449200

tissue_or_cell_type

Purified protein assay

Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 991–1003

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human proteins · source_derived_draft · unverified_draft

### mtrr-supports-mmab-in-vitro Purified human MTRR coupled cob(II)alamin reduction to MMAB-dependent adenosylcobalamin synthesis in vitro. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Human MTRR supported B12 activation in a test-tube system; this does not establish its mitochondrial role. organism: Homo sapiens tissue_or_cell_type: Purified protein assay experimental_model: Purified human proteins limitations: MTRR coupling in vitro does not identify the physiological mitochondrial electron donor. exposure: Purified MTRR plus MMAB and reductants cross_nutrient: true evidence_location: Indexed primary abstract [leal-2004-human-mmab] Human ATP:Cob(I)alamin adenosyltransferase and its interaction with methionine synthase reductase. (2004). https://pubmed.ncbi.nlm.nih.gov/15347655/ DOI: 10.1074/jbc.m405449200

cross_nutrient

true

evidence_span

{"source_cache": "artifacts/iodine-synthesis-sources/37654510.txt", "start_char": 9069, "end_char": 10489, "text_sha256": "5e0dc84da55832b58d1a1ad6c3a327551b878ef108389abf34b7eda4dcc8b7a1", "text_characters": 1420, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."}

experimental_model

Purified soluble human IYD reconstituted with FMN or synthetic 2-prime-deoxyFMN

exposure

Human IYD reconstituted with FMN or synthetic 2-prime-deoxyFMN; Table 1 kcat/Km 5.0 versus 0.97 x 10^3 M^-1 s^-1; kcat 0.052 versus 0.32 s^-1.

limitations

Synthetic cofactor substitution is not riboflavin deficiency; kcat/Km and kcat are different measurements. Table 1 native-FMN kinetic comparator is cited from previous work; reconstituted FMN was used for binding comparisons.

nutrient_topic

Iodine research collection; topical membership is not evidence of a direct dietary effect. · Iodine

organism

Homo sapiens recombinant protein

plain_language

A small change to FMN weakened overall substrate processing even though the saturated enzyme turned over faster.

primary_references

[iodine-syn-iyd2023] The 2'-hydroxy group of flavin mononucleotide influences the catalytic function and promiscuity of the flavoprotein iodotyrosine dehalogenase. (2023). https://pubmed.ncbi.nlm.nih.gov/37654510/ DOI: 10.1039/d3cb00094j

tissue_or_cell_type

Purified enzyme

Iodine: thyroid hormone production, deficiency, excess and nutrient interactions (2026-09-17) · lines 730–742

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified soluble human IYD reconstituted with FMN or synthetic 2-prime-deoxyFMN · source_derived_draft · unverified_draft

### iodine-syn-iyd-cofactor-substitution Replacing FMN with 2-prime-deoxyFMN in human IYD lowered iodotyrosine dehalogenation efficiency by more than fivefold while increasing turnover number by more than sixfold. Condition category: normal nutrient_topic: Iodine research collection; topical membership is not evidence of a direct dietary effect. plain_language: A small change to FMN weakened overall substrate processing even though the saturated enzyme turned over faster. organism: Homo sapiens recombinant protein tissue_or_cell_type: Purified enzyme experimental_model: Purified soluble human IYD reconstituted with FMN or synthetic 2-prime-deoxyFMN limitations: Synthetic cofactor substitution is not riboflavin deficiency; kcat/Km and kcat are different measurements. Table 1 native-FMN kinetic comparator is cited from previous work; reconstituted FMN was used for binding comparisons. exposure: Human IYD reconstituted with FMN or synthetic 2-prime-deoxyFMN; Table 1 kcat/Km 5.0 versus 0.97 x 10^3 M^-1 s^-1; kcat 0.052 versus 0.32 s^-1. cross_nutrient: true evidence_span: {"source_cache": "artifacts/iodine-synthesis-sources/37654510.txt", "start_char": 9069, "end_char": 10489, "text_sha256": "5e0dc84da55832b58d1a1ad6c3a327551b878ef108389abf34b7eda4dcc8b7a1", "text_characters": 1420, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."} [iodine-syn-iyd2023] The 2'-hydroxy group of flavin mononucleotide influences the catalytic function and promiscuity of the flavoprotein iodotyrosine dehalogenase. (2023). https://pubmed.ncbi.nlm.nih.gov/37654510/ DOI: 10.1039/d3cb00094j

cross_nutrient

true

evidence_span

{"source_cache": "artifacts/iodine-synthesis-sources/25395621.txt", "start_char": 11103, "end_char": 12723, "text_sha256": "726c34262182d49a45a4741a29a49ef70bf6d529c79d75cfbb0e9ea59ffd256b", "text_characters": 1620, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."}

experimental_model

Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration

exposure

0–70 micromolar [125I]DIT; sodium dithionite supplies reducing equivalents.

limitations

Anchor-deleted enzyme and artificial reductant; does not identify the physiological electron donor.

nutrient_topic

Iodine research collection; topical membership is not evidence of a direct dietary effect. · Iodine

organism

Homo sapiens recombinant protein

plain_language

IYD recovers iodine from leftover iodinated tyrosine.

primary_references

[iodine-syn-iyd2015] A switch between one- and two-electron chemistry of the human flavoprotein iodotyrosine deiodinase is controlled by substrate. (2015). https://pubmed.ncbi.nlm.nih.gov/25395621/ DOI: 10.1074/jbc.m114.605964

tissue_or_cell_type

Purified soluble IYD

Iodine: thyroid hormone production, deficiency, excess and nutrient interactions (2026-09-17) · lines 688–700

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration · source_derived_draft · unverified_draft

### iodine-syn-iyd-dit-salvage Purified soluble human IYD released radiolabeled iodide from diiodotyrosine during reductive enzyme assays. Condition category: normal nutrient_topic: Iodine research collection; topical membership is not evidence of a direct dietary effect. plain_language: IYD recovers iodine from leftover iodinated tyrosine. organism: Homo sapiens recombinant protein tissue_or_cell_type: Purified soluble IYD experimental_model: Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration limitations: Anchor-deleted enzyme and artificial reductant; does not identify the physiological electron donor. exposure: 0–70 micromolar [125I]DIT; sodium dithionite supplies reducing equivalents. cross_nutrient: true evidence_span: {"source_cache": "artifacts/iodine-synthesis-sources/25395621.txt", "start_char": 11103, "end_char": 12723, "text_sha256": "726c34262182d49a45a4741a29a49ef70bf6d529c79d75cfbb0e9ea59ffd256b", "text_characters": 1620, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."} [iodine-syn-iyd2015] A switch between one- and two-electron chemistry of the human flavoprotein iodotyrosine deiodinase is controlled by substrate. (2015). https://pubmed.ncbi.nlm.nih.gov/25395621/ DOI: 10.1074/jbc.m114.605964

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

true

evidence_span

{"source_cache": "artifacts/iodine-synthesis-sources/18434651.json", "json_field": "abstractText", "text_sha256": "f257956854445e268691cd3df1388ca16cea3f41320a48753df200a381c56431", "text_characters": 914, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."}

experimental_model

Four selected patients from three unrelated families plus in-vitro mutant enzyme assays

exposure

Two missense variants and one three-base-pair deletion; no nutrient-restriction experiment.

limitations

Abstract does not provide exact variant residues or assay dose.

nutrient_topic

Iodine research collection; topical membership is not evidence of a direct dietary effect. · Iodine

organism

Homo sapiens proteins

plain_language

Genetic defects can disable iodine recycling.

primary_references

[iodine-syn-iyd2008] Mutations in the iodotyrosine deiodinase gene and hypothyroidism. (2008). https://pubmed.ncbi.nlm.nih.gov/18434651/ DOI: 10.1056/nejmoa0706819

tissue_or_cell_type

In-vitro enzyme assays

trigger_kind

machinery_impairment Imported condition classification; unverified.

Iodine: thyroid hormone production, deficiency, excess and nutrient interactions (2026-09-17) · lines 744–756

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Four selected patients from three unrelated families plus in-vitro mutant enzyme assays · source_derived_draft · unverified_draft

### iodine-syn-iyd-mutant-activity The IYD variants identified in four affected patients showed markedly reduced iodotyrosine-deiodinase activity in vitro. Condition category: machinery_impairment nutrient_topic: Iodine research collection; topical membership is not evidence of a direct dietary effect. plain_language: Genetic defects can disable iodine recycling. organism: Homo sapiens proteins tissue_or_cell_type: In-vitro enzyme assays experimental_model: Four selected patients from three unrelated families plus in-vitro mutant enzyme assays limitations: Abstract does not provide exact variant residues or assay dose. exposure: Two missense variants and one three-base-pair deletion; no nutrient-restriction experiment. cross_nutrient: true evidence_span: {"source_cache": "artifacts/iodine-synthesis-sources/18434651.json", "json_field": "abstractText", "text_sha256": "f257956854445e268691cd3df1388ca16cea3f41320a48753df200a381c56431", "text_characters": 914, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."} [iodine-syn-iyd2008] Mutations in the iodotyrosine deiodinase gene and hypothyroidism. (2008). https://pubmed.ncbi.nlm.nih.gov/18434651/ DOI: 10.1056/nejmoa0706819

cross_nutrient

true

evidence_span

{"source_cache": "artifacts/iodine-synthesis-sources/25395621.txt", "start_char": 4223, "end_char": 4943, "text_sha256": "5567eccc06be2559ce51e8a2640697678a8fd3c1216896997568a9341da5a73b", "text_characters": 720, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."}

experimental_model

Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration

exposure

Reductive titration with versus without active-site ligand.

limitations

An inert fluorotyrosine probe demonstrates cofactor control, not physiological fluoride displacement.

nutrient_topic

Iodine research collection; topical membership is not evidence of a direct dietary effect. · Iodine

organism

Homo sapiens recombinant protein

plain_language

Substrate-like binding changes which FMN redox state the enzyme can stabilize.

primary_references

[iodine-syn-iyd2015] A switch between one- and two-electron chemistry of the human flavoprotein iodotyrosine deiodinase is controlled by substrate. (2015). https://pubmed.ncbi.nlm.nih.gov/25395621/ DOI: 10.1074/jbc.m114.605964

tissue_or_cell_type

Purified soluble IYD

Iodine: thyroid hormone production, deficiency, excess and nutrient interactions (2026-09-17) · lines 716–728

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration · source_derived_draft · unverified_draft

### iodine-syn-iyd-redox-switch The substrate analog 3-fluoro-L-tyrosine stabilized a one-electron-reduced FMN semiquinone during reductive titration of soluble human IYD. Condition category: normal nutrient_topic: Iodine research collection; topical membership is not evidence of a direct dietary effect. plain_language: Substrate-like binding changes which FMN redox state the enzyme can stabilize. organism: Homo sapiens recombinant protein tissue_or_cell_type: Purified soluble IYD experimental_model: Recombinant human IYD lacking residues 1–31; crystallography, radiotracer kinetics and redox titration limitations: An inert fluorotyrosine probe demonstrates cofactor control, not physiological fluoride displacement. exposure: Reductive titration with versus without active-site ligand. cross_nutrient: true evidence_span: {"source_cache": "artifacts/iodine-synthesis-sources/25395621.txt", "start_char": 4223, "end_char": 4943, "text_sha256": "5567eccc06be2559ce51e8a2640697678a8fd3c1216896997568a9341da5a73b", "text_characters": 720, "note": "Exact publisher passage retained in the cited local source cache; locator and digest supplied here."} [iodine-syn-iyd2015] A switch between one- and two-electron chemistry of the human flavoprotein iodotyrosine deiodinase is controlled by substrate. (2015). https://pubmed.ncbi.nlm.nih.gov/25395621/ DOI: 10.1074/jbc.m114.605964

cross_nutrient

true

experimental_model

Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution

exposure

Coupled assay used 50 micrograms/mL PPCDC with downstream COASY and 5 mM ATP; downstream ATP use is not assigned to PPCDC itself.

limitations

Coupled-assay confirmation and HPLC reconstitution; no dietary riboflavin depletion/repletion was tested.

nutrient_topic

Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect. · Pantothenate (vitamin B5)

organism

Homo sapiens

plain_language

PPCDC removes the cysteine carboxyl group to produce the next CoA intermediate.

primary_references

[b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200

tissue_or_cell_type

Purified recombinant protein; no intact tissue

Pantothenic acid (vitamin B5): coenzyme A, deficiency and nutrient interactions (2026-09-17) · lines 548–559

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution · source_derived_draft · unverified_draft

### b5-bio-ppcdc-decarboxylation Recombinant human PPCDC converted phosphopantothenoylcysteine to 4′-phosphopantetheine, verified by coupled enzyme assays and pathway reconstitution. Condition category: normal nutrient_topic: Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect. plain_language: PPCDC removes the cysteine carboxyl group to produce the next CoA intermediate. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution limitations: Coupled-assay confirmation and HPLC reconstitution; no dietary riboflavin depletion/repletion was tested. exposure: Coupled assay used 50 micrograms/mL PPCDC with downstream COASY and 5 mM ATP; downstream ATP use is not assigned to PPCDC itself. cross_nutrient: true [b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200