DLD

cross_nutrient

B1 performs E1 carbon chemistry; B2-derived FAD and the niacin-related NAD cofactor participate in the separate shared E3 reaction.

evidence

[{"paper_key": "brautigam-2005-dld", "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

Human DLD crystallography with NAD+ and NADH.

limitations

Cofactor chemistry does not establish dietary B2/B3 limitation or prove rescue of B1 deficiency.

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 shared E3 protein resets reduced lipoyl carriers using the B2-derived flavin and B3-related NAD system, allowing another round of B1-dependent turnover.

primary_references

[brautigam-2005-dld] Crystal structure of human dihydrolipoamide dehydrogenase: NAD+/NADH binding and the structural basis of disease-causing mutations (2005). https://pubmed.ncbi.nlm.nih.gov/15946682/ DOI: 10.1016/j.jmb.2005.05.014

tissue_or_cell_type

Purified enzyme

Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 717–729

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human DLD crystallography with NAD+ and NADH. · source_derived_draft · unverified_draft

### b1-dld-fad-nad-lipoyl-regeneration Human DLD uses bound FAD and transiently bound NAD+ to oxidize dihydrolipoamide; NADH-bound structures place its nicotinamide ring beside FAD. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: The shared E3 protein resets reduced lipoyl carriers using the B2-derived flavin and B3-related NAD system, allowing another round of B1-dependent turnover. organism: Homo sapiens tissue_or_cell_type: Purified enzyme experimental_model: Human DLD crystallography with NAD+ and NADH. limitations: Cofactor chemistry does not establish dietary B2/B3 limitation or prove rescue of B1 deficiency. evidence: [{"paper_key": "brautigam-2005-dld", "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: B1 performs E1 carbon chemistry; B2-derived FAD and the niacin-related NAD cofactor participate in the separate shared E3 reaction. nutrient: Thiamine (vitamin B1) [brautigam-2005-dld] Crystal structure of human dihydrolipoamide dehydrogenase: NAD+/NADH binding and the structural basis of disease-causing mutations (2005). https://pubmed.ncbi.nlm.nih.gov/15946682/ DOI: 10.1016/j.jmb.2005.05.014

availability_state

nutrient_deficiency Imported condition classification; unverified.

cross_nutrient

Connects B2-dependent DLD abundance to the canonical B1-dependent mitochondrial complexes; this study does not demonstrate failure of thiamine treatment.

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 compared with matched replete medium.

limitations

No direct PDH/OGDH flux or thiamine-response experiment; selective loss must not be generalized to all flavoproteins.

nutrient_topic

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

organism

Homo sapiens

plain_language

B2 withdrawal destabilized selected flavoproteins, including the shared DLD 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 cell proteomics

trigger_kind

nutrient_deficiency Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 622–634

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-dld DLD protein abundance decreased in riboflavin-depleted human 143B cells, while many other mitochondrial matrix flavoproteins did not decline. Condition category: nutrient_deficiency nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: B2 withdrawal destabilized selected flavoproteins, including the shared DLD enzyme. organism: Homo sapiens tissue_or_cell_type: 143B cell proteomics experimental_model: Human 143B cells and mouse adult fibroblasts, riboflavin-free medium and separate DPI interventions. limitations: No direct PDH/OGDH flux or thiamine-response experiment; selective loss must not be generalized to all flavoproteins. exposure: Riboflavin-free medium compared with matched replete medium. cross_nutrient: Connects B2-dependent DLD abundance to the canonical B1-dependent mitochondrial complexes; this study does not demonstrate failure of thiamine treatment. 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

evidence_access

Primary full text, pathway background

experimental_model

Established pathway shown in a human ECHS1 disease/biochemistry study; not a new BCKDH assay in that paper.

limitations

Cofactor and catalytic evidence is separately linked from existing ThDP/DLD records.

nutrient_topic

L-Isoleucine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Isoleucine

plain_language

A shared BCAA enzyme commits the carbon skeleton to further breakdown.

primary_references

Clinical and biochemical characterization of four patients with mutations in ECHS1. · 2015 · https://pubmed.ncbi.nlm.nih.gov/26081110/ · DOI 10.1186/s13023-015-0290-1

L-Isoleucine: transport, translation, catabolism and cross-nutrient mechanisms (2026-09-19) · lines 170–176

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Established pathway shown in a human ECHS1 disease/biochemistry study; not a new BCKDH assay in that paper. · source_derived_draft · unverified_draft

## isoleucine-bckdh-carbon-step A shared BCAA enzyme commits the carbon skeleton to further breakdown. The isoleucine pathway in the primary biochemical study places BCKDH-mediated oxidative decarboxylation of the branched ketoacid upstream of 2-methylbutyryl-CoA. Model: Established pathway shown in a human ECHS1 disease/biochemistry study; not a new BCKDH assay in that paper. Limitations: Cofactor and catalytic evidence is separately linked from existing ThDP/DLD records. Evidence access: Primary full text, pathway background Clinical and biochemical characterization of four patients with mutations in ECHS1. · 2015 · https://pubmed.ncbi.nlm.nih.gov/26081110/ · DOI 10.1186/s13023-015-0290-1

cross_nutrient

B6-dependent GLDC precedes lipoyl-carrier transfer and folate-dependent AMT chemistry.

experimental_model

Purified human AMT structures and mutational analyses

limitations

AMT is the directly examined human enzyme; this study did not test dietary B6 depletion or the entire pathway flux.

nutrient_topic

Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6

organism

Homo sapiens

plain_language

Glycine cleavage connects its B6-dependent first step to a separate folate-dependent step.

primary_references

[b6-amt-2005] Crystal structure of human T-protein of glycine cleavage system at 2.0 A resolution and its implication for understanding non-ketotic hyperglycinemia. (2005). https://pubmed.ncbi.nlm.nih.gov/16051266/ DOI: 10.1016/j.jmb.2005.06.056

tissue_or_cell_type

Purified recombinant protein; no intact tissue

Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 682–692

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

### b6-met-amt-onecarbon Human AMT transfers the aminomethyl-lipoyl intermediate's carbon to tetrahydrofolate, yielding 5,10-methylene-THF, ammonia and reduced H-protein. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Glycine cleavage connects its B6-dependent first step to a separate folate-dependent step. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified human AMT structures and mutational analyses limitations: AMT is the directly examined human enzyme; this study did not test dietary B6 depletion or the entire pathway flux. cross_nutrient: B6-dependent GLDC precedes lipoyl-carrier transfer and folate-dependent AMT chemistry. [b6-amt-2005] Crystal structure of human T-protein of glycine cleavage system at 2.0 A resolution and its implication for understanding non-ketotic hyperglycinemia. (2005). https://pubmed.ncbi.nlm.nih.gov/16051266/ DOI: 10.1016/j.jmb.2005.06.056

cross_nutrient

B1-dependent lysine catabolism converges on the same lipoyl, CoA and NAD/FAD machinery used in OGDH.

evidence

[{"paper_key": "nemeria-2018-oadh", "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

Human recombinant component reconstitution.

limitations

Reconstituted proteins; sharing does not establish competition for limiting subunits in vivo.

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

Lysine-related carbon disposal uses a different B1-dependent E1, while sharing the downstream E2 and E3 proteins with a TCA-cycle enzyme.

primary_references

[nemeria-2018-oadh] The mitochondrial 2-oxoadipate and 2-oxoglutarate dehydrogenase complexes share their E2 and E3 components for their function and both generate reactive oxygen species (2018). https://pubmed.ncbi.nlm.nih.gov/29191460/ DOI: 10.1016/j.freeradbiomed.2017.11.018

tissue_or_cell_type

Purified complex

Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 869–881

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

### b1-dhtkd1-recruits-shared-dlst-dld Human DHTKD1 supported 2-oxoadipate dehydrogenase activity when combined with the DLST and DLD components also used by OGDH. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: Lysine-related carbon disposal uses a different B1-dependent E1, while sharing the downstream E2 and E3 proteins with a TCA-cycle enzyme. organism: Homo sapiens tissue_or_cell_type: Purified complex experimental_model: Human recombinant component reconstitution. limitations: Reconstituted proteins; sharing does not establish competition for limiting subunits in vivo. evidence: [{"paper_key": "nemeria-2018-oadh", "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: B1-dependent lysine catabolism converges on the same lipoyl, CoA and NAD/FAD machinery used in OGDH. nutrient: Thiamine (vitamin B1) [nemeria-2018-oadh] The mitochondrial 2-oxoadipate and 2-oxoglutarate dehydrogenase complexes share their E2 and E3 components for their function and both generate reactive oxygen species (2018). https://pubmed.ncbi.nlm.nih.gov/29191460/ DOI: 10.1016/j.freeradbiomed.2017.11.018

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

cross_nutrient

B1, B5-derived CoA, B2-derived FAD and niacin-related NAD act at different steps of one complex.

evidence

[{"paper_key": "nemeria-2014-ogdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["p-28"], "locator": "The reaction medium contained the following in 1.0 ml", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}]

experimental_model

Reconstituted human multienzyme assay.

limitations

NADH assay measures overall complex turnover, not every intermediate independently.

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

B1-dependent E1 feeds a lipoyl/CoA transfer pathway, and E3 transfers the resulting reducing equivalents to NAD.

primary_references

[nemeria-2014-ogdh] Human 2-oxoglutarate dehydrogenase complex E1 component forms a thiamin-derived radical by aerobic oxidation of the enamine intermediate (2014). https://pubmed.ncbi.nlm.nih.gov/25210035/ DOI: 10.1074/jbc.m114.591073

tissue_or_cell_type

Purified enzyme complex

Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 855–867

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

### b1-ogdh-complex-couples-succinyl-nadh Human OGDH, lipoylated DLST and DLD assembled into an active complex coupling 2-oxoglutarate oxidation to NADH production in the CoA-containing assay. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: B1-dependent E1 feeds a lipoyl/CoA transfer pathway, and E3 transfers the resulting reducing equivalents to NAD. organism: Homo sapiens tissue_or_cell_type: Purified enzyme complex experimental_model: Reconstituted human multienzyme assay. limitations: NADH assay measures overall complex turnover, not every intermediate independently. evidence: [{"paper_key": "nemeria-2014-ogdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["p-28"], "locator": "The reaction medium contained the following in 1.0 ml", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}] cross_nutrient: B1, B5-derived CoA, B2-derived FAD and niacin-related NAD act at different steps of one complex. nutrient: Thiamine (vitamin B1) [nemeria-2014-ogdh] Human 2-oxoglutarate dehydrogenase complex E1 component forms a thiamin-derived radical by aerobic oxidation of the enamine intermediate (2014). https://pubmed.ncbi.nlm.nih.gov/25210035/ DOI: 10.1074/jbc.m114.591073

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_spans

[{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10341545", "locator": "XML .//body//p", "paragraph_index": 5, "char_start": 0, "char_end": 502, "evidence_access": "full-text"}, {"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10341545", "locator": "XML .//body//p", "paragraph_index": 6, "char_start": 0, "char_end": 1435, "evidence_access": "full-text"}]

experimental_model

Recombinant human DLD variants expressed in E. coli BL21(DE3), FAD quantification, activity, chromatography and crystallography.

exposure

G101del mutagenesis; FAD quantification and calibrated size exclusion.

limitations

Low expression and preparation heterogeneity were reported; no riboflavin-rescue experiment.

nutrient_topic

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

organism

Homo sapiens

plain_language

A different DLD alteration disrupted both flavin retention and protein assembly.

primary_references

[szabo-2023-dld-variants] Structural and Biochemical Investigation of Selected Pathogenic Mutants of the Human Dihydrolipoamide Dehydrogenase (2023). https://pubmed.ncbi.nlm.nih.gov/37446004/ DOI: 10.3390/ijms241310826

tissue_or_cell_type

Purified recombinant DLD

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 861–872

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human DLD variants expressed in E. coli BL21(DE3), FAD quantification, activity, chromatography and crystallography. · source_derived_draft · unverified_draft

### b2-met-dld-g101del-fad-retention Human DLD G101del retained about 0.07 FAD per monomer in the recombinant preparation; size-exclusion analysis also indicated loss of its normal dimeric assembly. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: A different DLD alteration disrupted both flavin retention and protein assembly. organism: Homo sapiens tissue_or_cell_type: Purified recombinant DLD experimental_model: Recombinant human DLD variants expressed in E. coli BL21(DE3), FAD quantification, activity, chromatography and crystallography. limitations: Low expression and preparation heterogeneity were reported; no riboflavin-rescue experiment. exposure: G101del mutagenesis; FAD quantification and calibrated size exclusion. evidence_spans: [{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10341545", "locator": "XML .//body//p", "paragraph_index": 5, "char_start": 0, "char_end": 502, "evidence_access": "full-text"}, {"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10341545", "locator": "XML .//body//p", "paragraph_index": 6, "char_start": 0, "char_end": 1435, "evidence_access": "full-text"}] [szabo-2023-dld-variants] Structural and Biochemical Investigation of Selected Pathogenic Mutants of the Human Dihydrolipoamide Dehydrogenase (2023). https://pubmed.ncbi.nlm.nih.gov/37446004/ DOI: 10.3390/ijms241310826

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

DLD is reused from the B1 complexes; its flavin/NAD step is distinct from upstream thiamine diphosphate chemistry.

evidence_spans

[{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10341545", "locator": "XML .//body//p", "paragraph_index": 19, "char_start": 0, "char_end": 871, "evidence_access": "full-text"}]

experimental_model

Recombinant human DLD variants expressed in E. coli BL21(DE3), FAD quantification, activity, chromatography and crystallography.

exposure

I12T mutagenesis, purified-protein FAD and activity assays.

limitations

Purification instability can affect measured occupancy; correlation does not prove FAD loss alone caused all activity loss.

nutrient_topic

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

organism

Homo sapiens

plain_language

This DLD variant poorly retained FAD and had very low catalytic activity.

primary_references

[szabo-2023-dld-variants] Structural and Biochemical Investigation of Selected Pathogenic Mutants of the Human Dihydrolipoamide Dehydrogenase (2023). https://pubmed.ncbi.nlm.nih.gov/37446004/ DOI: 10.3390/ijms241310826

tissue_or_cell_type

Recombinant DLD expressed in E. coli

trigger_kind

machinery_impairment Imported condition classification; unverified.

Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 847–859

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human DLD variants expressed in E. coli BL21(DE3), FAD quantification, activity, chromatography and crystallography. · source_derived_draft · unverified_draft

### b2-met-dld-i12t-fad-retention Purified human DLD I12T retained about 0.15 FAD per monomer versus approximately one in wild type, with forward and reverse activities of about 8% and 2%. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: This DLD variant poorly retained FAD and had very low catalytic activity. organism: Homo sapiens tissue_or_cell_type: Recombinant DLD expressed in E. coli experimental_model: Recombinant human DLD variants expressed in E. coli BL21(DE3), FAD quantification, activity, chromatography and crystallography. limitations: Purification instability can affect measured occupancy; correlation does not prove FAD loss alone caused all activity loss. exposure: I12T mutagenesis, purified-protein FAD and activity assays. cross_nutrient: DLD is reused from the B1 complexes; its flavin/NAD step is distinct from upstream thiamine diphosphate chemistry. evidence_spans: [{"source_bundle": "artifacts/riboflavin_metabolism_sources.json", "source_key": "PMC10341545", "locator": "XML .//body//p", "paragraph_index": 19, "char_start": 0, "char_end": 871, "evidence_access": "full-text"}] [szabo-2023-dld-variants] Structural and Biochemical Investigation of Selected Pathogenic Mutants of the Human Dihydrolipoamide Dehydrogenase (2023). https://pubmed.ncbi.nlm.nih.gov/37446004/ DOI: 10.3390/ijms241310826

experimental_model

Recombinant human DHTKD1 and DLST; structural and biochemical assays; Two human patients; fibroblast isotope tracing and genetic complementation

limitations

DHTKD1 is the E1 component, not a stand-alone enzyme performing every complex reaction.

organism

Homo sapiens

plain_language

A three-enzyme complex converts the carbon skeleton into glutaryl-CoA.

primary_references

[bezerra2020] Crystal structure and interaction studies of human DHTKD1 provide insight into a mitochondrial megacomplex in lysine catabolism (2020). https://pmc.ncbi.nlm.nih.gov/articles/PMC7340257/ DOI: 10.1107/S205225252000696X [danhauser2012] DHTKD1 mutations cause 2-aminoadipic and 2-oxoadipic aciduria (2012). https://pmc.ncbi.nlm.nih.gov/articles/PMC3516599/ DOI: 10.1016/j.ajhg.2012.10.006

tissue_or_cell_type

Mitochondrial matrix

L-Lysine: mechanism-first literature curation (2026-09-17) · lines 125–134

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human DHTKD1 and DLST; structural and biochemical assays; Two human patients; fibroblast isotope tracing and genetic complementation · source_derived_draft · unverified_draft

### oxoadipate-dehydrogenase-complex DHTKD1 with DLST and DLD supports oxidative decarboxylation of 2-oxoadipate to glutaryl-CoA, with NADH and carbon dioxide formation. Plain language: A three-enzyme complex converts the carbon skeleton into glutaryl-CoA. Condition category: normal organism: Homo sapiens tissue_or_cell_type: Mitochondrial matrix experimental_model: Recombinant human DHTKD1 and DLST; structural and biochemical assays; Two human patients; fibroblast isotope tracing and genetic complementation limitations: DHTKD1 is the E1 component, not a stand-alone enzyme performing every complex reaction. [bezerra2020] Crystal structure and interaction studies of human DHTKD1 provide insight into a mitochondrial megacomplex in lysine catabolism (2020). https://pmc.ncbi.nlm.nih.gov/articles/PMC7340257/ DOI: 10.1107/S205225252000696X [danhauser2012] DHTKD1 mutations cause 2-aminoadipic and 2-oxoadipic aciduria (2012). https://pmc.ncbi.nlm.nih.gov/articles/PMC3516599/ DOI: 10.1016/j.ajhg.2012.10.006