Magnesium-ATP complex

cross_nutrient

Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration.

experimental_model

Shark rectal-gland pump membrane fragments; stopped-flow RH421 fluorescence under Na-rich conditions.

limitations

Conclusion concerns E1-ATP; other pump conformations or Mg sites can behave differently.

nutrient_topic

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

organism

Shark

plain_language

The ATP-associated magnesium supports phosphorylation; free ATP can compete for that magnesium.

primary_references

[pilotelle-2009-nka] Mechanism of Mg2+ binding in the Na+,K+-ATPase (2009). https://pmc.ncbi.nlm.nih.gov/articles/PMC2711396/ DOI: 10.1016/j.bpj.2009.01.042

tissue_or_cell_type

Rectal-gland enzyme membrane fragments

Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 795–805

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Shark rectal-gland pump membrane fragments; stopped-flow RH421 fluorescence under Na-rich conditions. · source_derived_draft · unverified_draft

### mg-nka-atp-dominates-mg-binding Shark-pump kinetic fits assigned E1-ATP Mg affinity mainly to ATP coordination, after accounting for free ATP competition. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: The ATP-associated magnesium supports phosphorylation; free ATP can compete for that magnesium. organism: Shark tissue_or_cell_type: Rectal-gland enzyme membrane fragments experimental_model: Shark rectal-gland pump membrane fragments; stopped-flow RH421 fluorescence under Na-rich conditions. limitations: Conclusion concerns E1-ATP; other pump conformations or Mg sites can behave differently. cross_nutrient: Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration. [pilotelle-2009-nka] Mechanism of Mg2+ binding in the Na+,K+-ATPase (2009). https://pmc.ncbi.nlm.nih.gov/articles/PMC2711396/ DOI: 10.1016/j.bpj.2009.01.042

cross_nutrient

Magnesium-B6 activation chemistry.

evidence_location

Indexed abstract and publisher abstract; human enzyme findings only

experimental_model

Purified recombinant human and E. coli pyridoxal kinases.

exposure

MgATP versus ZnATP kinetic comparisons.

limitations

Metal preference depends on assay conditions and does not prove magnesium supplementation improves B6 status.

nutrient_topic

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

organism

Homo sapiens

plain_language

Magnesium helps supply ATP to B6 activation.

primary_references

[disalvo2004] Expression, purification, and kinetic constants for human and Escherichia coli pyridoxal kinases. (2004). https://pubmed.ncbi.nlm.nih.gov/15249053/ DOI: 10.1016/j.pep.2004.04.021

tissue_or_cell_type

Purified human enzyme

Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 189–201

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

### b6-transport-pdxk-mgatp Kinase kinetic experiments identified MgATP as the preferred phosphate-donor complex under the reported physiological assay conditions. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium helps supply ATP to B6 activation. organism: Homo sapiens tissue_or_cell_type: Purified human enzyme experimental_model: Purified recombinant human and E. coli pyridoxal kinases. limitations: Metal preference depends on assay conditions and does not prove magnesium supplementation improves B6 status. exposure: MgATP versus ZnATP kinetic comparisons. evidence_location: Indexed abstract and publisher abstract; human enzyme findings only cross_nutrient: Magnesium-B6 activation chemistry. [disalvo2004] Expression, purification, and kinetic constants for human and Escherichia coli pyridoxal kinases. (2004). https://pubmed.ncbi.nlm.nih.gov/15249053/ DOI: 10.1016/j.pep.2004.04.021

evidence_span

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experimental_model

Phosphorylated CFTR channel nucleotide assays

exposure

Hydrolyzable nucleotides, analogues and Mg-free ATP

limitations

Records the measured Mg/nucleotide dependence, not the paper’s historical assignment of opening to NBD1 hydrolysis.

nutrient_topic

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

organism

Human CFTR in expression preparations

plain_language

Magnesium and ATP are part of the working channel system; chloride alone is insufficient.

primary_references

[chloride-p1718606] Nucleoside triphosphates are required to open the CFTR chloride channel. (1991). https://pubmed.ncbi.nlm.nih.gov/1718606/ DOI: 10.1016/0092-8674(91)90072-7

tissue_or_cell_type

Cytosolic channel face

Chloride: transport, acid-base balance, nutrient interactions and loss states (2026-09-17) · lines 250–261

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Phosphorylated CFTR channel nucleotide assays · source_derived_draft · unverified_draft

### chloride-cftr-mgatp Phosphorylated CFTR channels opened with ATP but not Mg-free ATP in this preparation. Condition category: normal nutrient_topic: Chloride research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium and ATP are part of the working channel system; chloride alone is insufficient. organism: Human CFTR in expression preparations tissue_or_cell_type: Cytosolic channel face experimental_model: Phosphorylated CFTR channel nucleotide assays limitations: Records the measured Mg/nucleotide dependence, not the paper’s historical assignment of opening to NBD1 hydrolysis. exposure: Hydrolyzable nucleotides, analogues and Mg-free ATP evidence_span: {"source_cache": "artifacts/chloride-research/1718606.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a66a28a6b6c5d2abfee4d416aeddca8f38a48e343d2715f599c8c05998943f67", "start_char": 0, "end_char": 925, "text_sha256": "a66a28a6b6c5d2abfee4d416aeddca8f38a48e343d2715f599c8c05998943f67"} [chloride-p1718606] Nucleoside triphosphates are required to open the CFTR chloride channel. (1991). https://pubmed.ncbi.nlm.nih.gov/1718606/ DOI: 10.1016/0092-8674(91)90072-7

evidence_span

{"source_cache": "artifacts/citrulline-research/2788888.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "29b1553359d37a53c529b8a2b53ba646cca6b4b401ba7a9722e0e1f15510e676", "start_char": 0, "end_char": 1043, "text_sha256": "29b1553359d37a53c529b8a2b53ba646cca6b4b401ba7a9722e0e1f15510e676"}

experimental_model

Chemical modification and substrate protection of enzyme

exposure

Alpha-dicarbonyl modification with Mg-ATP protection

limitations

Protection assay identifies binding requirements; it is not a magnesium supplementation or depletion study.

nutrient_topic

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

organism

Human ASS1

plain_language

The active energy substrate is linked to magnesium, but more magnesium is not automatically rate-limiting.

primary_references

[citrulline-p2788888] Identification of essential arginine residue(s) for Mg-ATP binding of human argininosuccinate synthetase. (1989). https://pubmed.ncbi.nlm.nih.gov/2788888/

tissue_or_cell_type

ATP-binding region

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 164–175

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Chemical modification and substrate protection of enzyme · source_derived_draft · unverified_draft

### citrulline-ass1-mg-atp Mg-ATP almost completely protected human ASS1 against alpha-dicarbonyl inactivation, implicating arginine residues in its binding site. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: The active energy substrate is linked to magnesium, but more magnesium is not automatically rate-limiting. organism: Human ASS1 tissue_or_cell_type: ATP-binding region experimental_model: Chemical modification and substrate protection of enzyme limitations: Protection assay identifies binding requirements; it is not a magnesium supplementation or depletion study. exposure: Alpha-dicarbonyl modification with Mg-ATP protection evidence_span: {"source_cache": "artifacts/citrulline-research/2788888.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "29b1553359d37a53c529b8a2b53ba646cca6b4b401ba7a9722e0e1f15510e676", "start_char": 0, "end_char": 1043, "text_sha256": "29b1553359d37a53c529b8a2b53ba646cca6b4b401ba7a9722e0e1f15510e676"} [citrulline-p2788888] Identification of essential arginine residue(s) for Mg-ATP binding of human argininosuccinate synthetase. (1989). https://pubmed.ncbi.nlm.nih.gov/2788888/

cross_nutrient

Magnesium availability supports vitamin B1 activation or cofactor use in the specified preparation; this does not establish a dietary threshold or universal treatment failure.

experimental_model

Purified recombinant mouse TPK1; forward and reverse reaction kinetics.

limitations

ATP concentration shifted the optimum; in vitro values are not intake targets.

nutrient_topic

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

organism

Mus musculus

plain_language

More magnesium did not continuously increase B1 activation in this assay.

primary_references

[sambon-2022-tpk1] Product inhibition of mammalian thiamine pyrophosphokinase is an important mechanism for maintaining thiamine diphosphate homeostasis (2022). https://doi.org/10.1016/j.bbagen.2021.130071 DOI: 10.1016/j.bbagen.2021.130071

tissue_or_cell_type

Purified recombinant enzyme

Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 517–527

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant mouse TPK1; forward and reverse reaction kinetics. · source_derived_draft · unverified_draft

### mg-mouse-tpk-nonmonotonic Recombinant mouse TPK1 showed an Mg optimum followed by inhibition as Mg was increased at fixed ATP. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: More magnesium did not continuously increase B1 activation in this assay. organism: Mus musculus tissue_or_cell_type: Purified recombinant enzyme experimental_model: Purified recombinant mouse TPK1; forward and reverse reaction kinetics. limitations: ATP concentration shifted the optimum; in vitro values are not intake targets. cross_nutrient: Magnesium availability supports vitamin B1 activation or cofactor use in the specified preparation; this does not establish a dietary threshold or universal treatment failure. [sambon-2022-tpk1] Product inhibition of mammalian thiamine pyrophosphokinase is an important mechanism for maintaining thiamine diphosphate homeostasis (2022). https://doi.org/10.1016/j.bbagen.2021.130071 DOI: 10.1016/j.bbagen.2021.130071

cross_nutrient

Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration.

experimental_model

Pig-kidney Na/K-ATPase rapid-mixing phosphorylation; Na-containing, K-free medium; varied ATP and MgCl2.

limitations

Kinetic model, not proof of Mg-free catalysis; binding and phosphate transfer are distinct.

nutrient_topic

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

organism

Sus scrofa

plain_language

A requirement for magnesium does not prove that only a preformed MgATP molecule can bind.

primary_references

[campos-1992-nka] Effects of magnesium and ATP on pre-steady-state phosphorylation kinetics of the Na+,K(+)-ATPase (1992). https://pubmed.ncbi.nlm.nih.gov/1314673/ DOI: 10.1016/0005-2736(92)90161-e

tissue_or_cell_type

Kidney enzyme

Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 783–793

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Pig-kidney Na/K-ATPase rapid-mixing phosphorylation; Na-containing, K-free medium; varied ATP and MgCl2. · source_derived_draft · unverified_draft

### mg-nka-atp-binding-order-boundary The 1992 best-fit model allowed free ATP or MgATP to bind before productive Mg-dependent phosphorylation. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: A requirement for magnesium does not prove that only a preformed MgATP molecule can bind. organism: Sus scrofa tissue_or_cell_type: Kidney enzyme experimental_model: Pig-kidney Na/K-ATPase rapid-mixing phosphorylation; Na-containing, K-free medium; varied ATP and MgCl2. limitations: Kinetic model, not proof of Mg-free catalysis; binding and phosphate transfer are distinct. cross_nutrient: Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration. [campos-1992-nka] Effects of magnesium and ATP on pre-steady-state phosphorylation kinetics of the Na+,K(+)-ATPase (1992). https://pubmed.ncbi.nlm.nih.gov/1314673/ DOI: 10.1016/0005-2736(92)90161-e

cross_nutrient

Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration.

experimental_model

Phosphorylated pig-kidney Na/K-ATPase-ouabain complex crystallography.

limitations

Drug-stabilized inhibited state; it does not demonstrate physiological Mg transport.

nutrient_topic

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

organism

Sus scrofa

plain_language

Magnesium can occupy a membrane ion site distinct from the ATP-associated catalytic site.

primary_references

[laursen-2013-nka] Crystal structure of the high-affinity Na+K+-ATPase-ouabain complex with Mg2+ bound in the cation binding site (2013). https://pubmed.ncbi.nlm.nih.gov/23776223/ DOI: 10.1073/pnas.1222308110

tissue_or_cell_type

Kidney enzyme crystals

Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 845–855

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Phosphorylated pig-kidney Na/K-ATPase-ouabain complex crystallography. · source_derived_draft · unverified_draft

### mg-nka-distinct-transport-site Mg occupied cation transport site II in the ouabain-bound E2P pig-kidney pump structure. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium can occupy a membrane ion site distinct from the ATP-associated catalytic site. organism: Sus scrofa tissue_or_cell_type: Kidney enzyme crystals experimental_model: Phosphorylated pig-kidney Na/K-ATPase-ouabain complex crystallography. limitations: Drug-stabilized inhibited state; it does not demonstrate physiological Mg transport. cross_nutrient: Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration. [laursen-2013-nka] Crystal structure of the high-affinity Na+K+-ATPase-ouabain complex with Mg2+ bound in the cation binding site (2013). https://pubmed.ncbi.nlm.nih.gov/23776223/ DOI: 10.1073/pnas.1222308110

cross_nutrient

Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration.

experimental_model

Pig-kidney Na/K-ATPase rapid-mixing phosphorylation; Na-containing, K-free medium; varied ATP and MgCl2.

limitations

Na-containing, K-free assay; not the full physiological transport cycle.

nutrient_topic

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

organism

Sus scrofa

plain_language

Magnesium enables the ATP-driven phosphate-transfer step of the sodium pump.

primary_references

[campos-1992-nka] Effects of magnesium and ATP on pre-steady-state phosphorylation kinetics of the Na+,K(+)-ATPase (1992). https://pubmed.ncbi.nlm.nih.gov/1314673/ DOI: 10.1016/0005-2736(92)90161-e

tissue_or_cell_type

Kidney enzyme

Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 771–781

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Pig-kidney Na/K-ATPase rapid-mixing phosphorylation; Na-containing, K-free medium; varied ATP and MgCl2. · source_derived_draft · unverified_draft

### mg-nka-phosphorylation-requirement Pre-steady-state pig-kidney pump experiments identified Mg as an essential activator of ATP-dependent phosphorylation. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium enables the ATP-driven phosphate-transfer step of the sodium pump. organism: Sus scrofa tissue_or_cell_type: Kidney enzyme experimental_model: Pig-kidney Na/K-ATPase rapid-mixing phosphorylation; Na-containing, K-free medium; varied ATP and MgCl2. limitations: Na-containing, K-free assay; not the full physiological transport cycle. cross_nutrient: Magnesium-dependent ATP chemistry is coupled to sodium and potassium handling by the pump; serum magnesium is not the enzyme-site concentration. [campos-1992-nka] Effects of magnesium and ATP on pre-steady-state phosphorylation kinetics of the Na+,K(+)-ATPase (1992). https://pubmed.ncbi.nlm.nih.gov/1314673/ DOI: 10.1016/0005-2736(92)90161-e

cross_nutrient

Magnesium and thiamine-derived ThDP intersect at mitochondrial carbon metabolism; purified-enzyme responses do not measure whole-body energy supply.

experimental_model

Isolated pig-heart enzyme complex plus mitochondrial extracts; extract source not resolved in this curation; nucleotide/phosphate/Mg speciation experiments.

limitations

The paper assigns more than one inhibitory mechanism; their in vivo contributions were not measured.

nutrient_topic

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

organism

Sus scrofa

plain_language

ATP concentration can alter both free magnesium and nucleotide regulation of the enzyme.

primary_references

[rodriguez-2000-ogdh] Modulation of 2-oxoglutarate dehydrogenase complex by inorganic phosphate, Mg(2+), and other effectors (2000). https://pubmed.ncbi.nlm.nih.gov/10864444/ DOI: 10.1006/abbi.2000.1856

tissue_or_cell_type

Isolated heart enzyme; additional mitochondrial-extract source not resolved

Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 711–721

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Isolated pig-heart enzyme complex plus mitochondrial extracts; extract source not resolved in this curation; nucleotide/phosphate/Mg speciation experiments. · source_derived_draft · unverified_draft

### mg-ogdh-atp-chelation-inhibition The 2000 study attributed ATP inhibition to Mg chelation and an inhibitory effect of MgATP. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: ATP concentration can alter both free magnesium and nucleotide regulation of the enzyme. organism: Sus scrofa tissue_or_cell_type: Isolated heart enzyme; additional mitochondrial-extract source not resolved experimental_model: Isolated pig-heart enzyme complex plus mitochondrial extracts; extract source not resolved in this curation; nucleotide/phosphate/Mg speciation experiments. limitations: The paper assigns more than one inhibitory mechanism; their in vivo contributions were not measured. cross_nutrient: Magnesium and thiamine-derived ThDP intersect at mitochondrial carbon metabolism; purified-enzyme responses do not measure whole-body energy supply. [rodriguez-2000-ogdh] Modulation of 2-oxoglutarate dehydrogenase complex by inorganic phosphate, Mg(2+), and other effectors (2000). https://pubmed.ncbi.nlm.nih.gov/10864444/ DOI: 10.1006/abbi.2000.1856

cross_nutrient

Magnesium availability supports vitamin B1 activation or cofactor use in the specified preparation; this does not establish a dietary threshold or universal treatment failure.

experimental_model

Purified His-tagged recombinant human TPK1, steady-state kinetics and mutations.

limitations

Total concentrations and speciation must be distinguished; no human Mg cutoff follows.

nutrient_topic

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

organism

Homo sapiens

plain_language

The balance between ATP-bound and available magnesium affects activation of B1.

primary_references

[onozuka-2003-tpk1] Steady-state kinetics and mutational studies of recombinant human thiamin pyrophosphokinase (2003). https://pubmed.ncbi.nlm.nih.gov/12953792/ DOI: 10.3177/jnsv.49.156

tissue_or_cell_type

Purified recombinant enzyme

Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 493–503

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified His-tagged recombinant human TPK1, steady-state kinetics and mutations. · source_derived_draft · unverified_draft

### mg-tpk1-free-mg-restores-activity Mg2+ in excess over ATP restored human TPK1 activity at low MgATP concentrations compared with a 1:1 total Mg:ATP ratio. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: The balance between ATP-bound and available magnesium affects activation of B1. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme experimental_model: Purified His-tagged recombinant human TPK1, steady-state kinetics and mutations. limitations: Total concentrations and speciation must be distinguished; no human Mg cutoff follows. cross_nutrient: Magnesium availability supports vitamin B1 activation or cofactor use in the specified preparation; this does not establish a dietary threshold or universal treatment failure. [onozuka-2003-tpk1] Steady-state kinetics and mutational studies of recombinant human thiamin pyrophosphokinase (2003). https://pubmed.ncbi.nlm.nih.gov/12953792/ DOI: 10.3177/jnsv.49.156

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_location

Figure 3B,E

experimental_model

Human families, dried blood spots, recombinant PDXK variants.

exposure

ATPgammaS ITC; variable MgATP kinetics.

limitations

ATPgammaS is an analog; absence of detectable binding is assay-specific.

nutrient_topic

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

organism

Homo sapiens

plain_language

The variant disrupts nucleotide handling.

primary_references

[chelban2019] PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. (2019). https://pubmed.ncbi.nlm.nih.gov/31187503/ DOI: 10.1002/ana.25524

tissue_or_cell_type

Purified human enzyme

trigger_kind

machinery_impairment Imported condition classification; unverified.

Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 217–228

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human families, dried blood spots, recombinant PDXK variants. · source_derived_draft · unverified_draft

### b6-transport-pdxk-a228t-atp ATPgammaS binding was detected for wild-type PDXK but not A228T under the ITC conditions; A228T also required higher MgATP for half-maximal activity. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The variant disrupts nucleotide handling. organism: Homo sapiens tissue_or_cell_type: Purified human enzyme experimental_model: Human families, dried blood spots, recombinant PDXK variants. limitations: ATPgammaS is an analog; absence of detectable binding is assay-specific. exposure: ATPgammaS ITC; variable MgATP kinetics. evidence_location: Figure 3B,E [chelban2019] PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. (2019). https://pubmed.ncbi.nlm.nih.gov/31187503/ DOI: 10.1002/ana.25524

cross_nutrient

Potassium/sodium-B6 enzyme kinetics.

evidence_location

Full text: Metal binding and enzyme activity; Figure 1

experimental_model

Purified recombinant human PDXK kinetics and crystallography.

exposure

Kinetic assays at pH 7.3.

limitations

Lower Km is not a direct binding constant; results do not define dietary sodium/potassium effects.

nutrient_topic

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

organism

Homo sapiens

plain_language

Potassium and sodium affect different kinetic properties.

primary_references

[safo2007] Crystal Structure of human pyridoxal kinase: structural basis of M(+) and M(2+) activation. (2007). https://pubmed.ncbi.nlm.nih.gov/17766369/ DOI: 10.1110/ps.073022107

tissue_or_cell_type

Purified human enzyme

Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 203–215

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

### b6-transport-pdxk-k-na Human PDXK showed lower substrate Km with potassium than sodium, whereas sodium supported over twice the maximal activity. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Potassium and sodium affect different kinetic properties. organism: Homo sapiens tissue_or_cell_type: Purified human enzyme experimental_model: Purified recombinant human PDXK kinetics and crystallography. limitations: Lower Km is not a direct binding constant; results do not define dietary sodium/potassium effects. exposure: Kinetic assays at pH 7.3. evidence_location: Full text: Metal binding and enzyme activity; Figure 1 cross_nutrient: Potassium/sodium-B6 enzyme kinetics. [safo2007] Crystal Structure of human pyridoxal kinase: structural basis of M(+) and M(2+) activation. (2007). https://pubmed.ncbi.nlm.nih.gov/17766369/ DOI: 10.1110/ps.073022107

cross_nutrient

Mg-dependent ATP chemistry activates B1; it does not imply every later ThDP-binding event consumes ATP.

curation_note

Adds explicit phosphate-transfer/AMP-product detail to the existing magnesium collection.

evidence-scope

Recombinant enzyme

evidence_locator

Abstract

evidence_spans

[{"source_document": "artifacts/thiamine_transport_sources/sambon-2022-tpk1-source-record.json", "source_field": "resultList.result[0].abstractText", "start_char": 0, "end_char": 1689}]

experimental_model

Purified His-tagged human TPK1; ATP/Mg kinetics and mutagenesis.

limitations

Overall chemistry does not resolve substrate-binding order.

nutrient_topic

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

organism

Homo sapiens

plain_language

B1 activation uses ATP and releases AMP; it is not an ATP-to-ADP single-phosphate step.

primary_references

[onozuka-2003-tpk1] Steady-state kinetics and mutational studies of recombinant human thiamin pyrophosphokinase (2003). https://pubmed.ncbi.nlm.nih.gov/12953792/ DOI: 10.3177/jnsv.49.156 [sambon-2022-tpk1] Product inhibition of mammalian thiamine pyrophosphokinase is an important mechanism for maintaining thiamine diphosphate homeostasis (2022). https://doi.org/10.1016/j.bbagen.2021.130071 DOI: 10.1016/j.bbagen.2021.130071

reaction

thiamine + ATP -> thiamine diphosphate + AMP

related_existing_claim_keys

["mg-tpk1-thiamine-to-thdp"]

tissue_or_cell_type

Recombinant enzyme

Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 339–356

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified His-tagged human TPK1; ATP/Mg kinetics and mutagenesis. · source_derived_draft · unverified_draft

### b1-tpk1-atp-amp-stoichiometry TPK1 activation transfers ATP-derived diphosphoryl to thiamine, yielding ThDP and AMP in a magnesium-dependent reaction. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: B1 activation uses ATP and releases AMP; it is not an ATP-to-ADP single-phosphate step. organism: Homo sapiens tissue_or_cell_type: Recombinant enzyme experimental_model: Purified His-tagged human TPK1; ATP/Mg kinetics and mutagenesis. limitations: Overall chemistry does not resolve substrate-binding order. cross_nutrient: Mg-dependent ATP chemistry activates B1; it does not imply every later ThDP-binding event consumes ATP. reaction: thiamine + ATP -> thiamine diphosphate + AMP related_existing_claim_keys: ["mg-tpk1-thiamine-to-thdp"] curation_note: Adds explicit phosphate-transfer/AMP-product detail to the existing magnesium collection. evidence_spans: [{"source_document": "artifacts/thiamine_transport_sources/sambon-2022-tpk1-source-record.json", "source_field": "resultList.result[0].abstractText", "start_char": 0, "end_char": 1689}] evidence_locator: Abstract evidence-scope: Recombinant enzyme [onozuka-2003-tpk1] Steady-state kinetics and mutational studies of recombinant human thiamin pyrophosphokinase (2003). https://pubmed.ncbi.nlm.nih.gov/12953792/ DOI: 10.3177/jnsv.49.156 [sambon-2022-tpk1] Product inhibition of mammalian thiamine pyrophosphokinase is an important mechanism for maintaining thiamine diphosphate homeostasis (2022). https://doi.org/10.1016/j.bbagen.2021.130071 DOI: 10.1016/j.bbagen.2021.130071

cross_nutrient

Free ATP must be distinguished from its magnesium complex.

experimental_model

Rat beta-cell inside-out patches.

limitations

Excised patches do not reproduce all intact-cell metabolic regulation.

nutrient_topic

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

organism

Rat

plain_language

ATP can close the potassium channel through nucleotide regulation.

primary_references

[ashcroft-1989-magnesium] ATP-sensitive K+ channels in rat pancreatic beta-cells: modulation by ATP and Mg2+ ions (1989). https://pmc.ncbi.nlm.nih.gov/articles/PMC1189219/ DOI: 10.1113/jphysiol.1989.sp017765

tissue_or_cell_type

Pancreatic beta-cell membrane

Potassium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 786–796

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Rat beta-cell inside-out patches. · source_derived_draft · unverified_draft

### k-beta-atp-inhibition Free ATP and nonhydrolyzable ATP analogues inhibited beta-cell KATP channels without requiring phosphorylation. Condition category: normal nutrient_topic: Potassium research collection; topical membership is not evidence of a direct dietary effect. plain_language: ATP can close the potassium channel through nucleotide regulation. organism: Rat tissue_or_cell_type: Pancreatic beta-cell membrane experimental_model: Rat beta-cell inside-out patches. limitations: Excised patches do not reproduce all intact-cell metabolic regulation. cross_nutrient: Free ATP must be distinguished from its magnesium complex. [ashcroft-1989-magnesium] ATP-sensitive K+ channels in rat pancreatic beta-cells: modulation by ATP and Mg2+ ions (1989). https://pmc.ncbi.nlm.nih.gov/articles/PMC1189219/ DOI: 10.1113/jphysiol.1989.sp017765

cross_nutrient

Magnesium-nucleotide chemistry modifies potassium-channel gating; no dietary magnesium effect quantified.

experimental_model

Inside-out rat patches; Mg-free versus 2 mM Mg.

limitations

Assay concentrations are not clinical magnesium thresholds.

nutrient_topic

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

organism

Rat

plain_language

Magnesium changed how the potassium channel responded to total ATP.

primary_references

[ashcroft-1989-magnesium] ATP-sensitive K+ channels in rat pancreatic beta-cells: modulation by ATP and Mg2+ ions (1989). https://pmc.ncbi.nlm.nih.gov/articles/PMC1189219/ DOI: 10.1113/jphysiol.1989.sp017765

tissue_or_cell_type

Pancreatic beta-cell membrane

Potassium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 798–808

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Inside-out rat patches; Mg-free versus 2 mM Mg. · source_derived_draft · unverified_draft

### k-beta-mg-atp-speciation Adding 2 mM Mg shifted apparent total-ATP inhibition from Ki 4 to 26 micromolar in excised beta-cell patches. Condition category: normal nutrient_topic: Potassium research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium changed how the potassium channel responded to total ATP. organism: Rat tissue_or_cell_type: Pancreatic beta-cell membrane experimental_model: Inside-out rat patches; Mg-free versus 2 mM Mg. limitations: Assay concentrations are not clinical magnesium thresholds. cross_nutrient: Magnesium-nucleotide chemistry modifies potassium-channel gating; no dietary magnesium effect quantified. [ashcroft-1989-magnesium] ATP-sensitive K+ channels in rat pancreatic beta-cells: modulation by ATP and Mg2+ ions (1989). https://pmc.ncbi.nlm.nih.gov/articles/PMC1189219/ DOI: 10.1113/jphysiol.1989.sp017765

cross_nutrient

Potassium transport depends jointly on sodium and magnesium-supported ATP chemistry.

experimental_model

Resealed human erythrocyte ghosts; sided ion substitutions.

limitations

Sided activation adds to existing catalog flux/phosphorylation records; MgATP-only binding is not asserted.

nutrient_topic

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

organism

Human

plain_language

Potassium outside and sodium inside activate complementary sides of the pump.

primary_references

[garrahan-1967-pump] The stoicheiometry of the sodium pump (1967). https://pmc.ncbi.nlm.nih.gov/articles/PMC1365482/ DOI: 10.1113/jphysiol.1967.sp008297

tissue_or_cell_type

Erythrocyte membrane

Potassium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 575–585

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Resealed human erythrocyte ghosts; sided ion substitutions. · source_derived_draft · unverified_draft

### k-pump-extracellular-activation External potassium supported ouabain-sensitive ATP hydrolysis when erythrocyte ghosts contained sodium, ATP and magnesium. Condition category: normal nutrient_topic: Potassium research collection; topical membership is not evidence of a direct dietary effect. plain_language: Potassium outside and sodium inside activate complementary sides of the pump. organism: Human tissue_or_cell_type: Erythrocyte membrane experimental_model: Resealed human erythrocyte ghosts; sided ion substitutions. limitations: Sided activation adds to existing catalog flux/phosphorylation records; MgATP-only binding is not asserted. cross_nutrient: Potassium transport depends jointly on sodium and magnesium-supported ATP chemistry. [garrahan-1967-pump] The stoicheiometry of the sodium pump (1967). https://pmc.ncbi.nlm.nih.gov/articles/PMC1365482/ DOI: 10.1113/jphysiol.1967.sp008297

cross_nutrient

Mg-ATP supplies the phosphate donor for generating niacin-derived NADP+. NADP+ production is distinct from its later reduction to NADPH.

evidence_span

{"source_cache": "artifacts/niacin-redox-sources/nadk-human-2025.fulltext.txt", "locator": "Results", "start_char": 53525, "end_char": 54577, "file_sha256": "72c7b9625e1bf4137d6833adac6ae49fc108f2cd75bb4945c5b04d72a0355f9b", "text_sha256": "db49fc47ad605562e1c1cf93e1b39596505906831ae509e7ec0031485f84ba4f"}

experimental_model

Full-length recombinant human NADK; G6PD-coupled assay

exposure

5 mM MgATP; 0.1–2 mM NAD+; 1 mM additional MgCl2; 30°C

limitations

Scoped experimental observation; no dietary niacin or magnesium deficiency threshold or treatment benefit was tested.

nutrient_topic

Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)

organism

Homo sapiens

plain_language

The cytosolic kinase makes the phosphorylated cofactor using magnesium-associated ATP.

primary_references

[nadk-human-2025] Cryo-EM structure and regulation of human NAD kinase. (2025). https://pubmed.ncbi.nlm.nih.gov/39854463/ DOI: 10.1126/sciadv.ads2664

tissue_or_cell_type

Purified enzyme

Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 831–843

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Full-length recombinant human NADK; G6PD-coupled assay · source_derived_draft · unverified_draft

### b3-redox-nadk-mgatp Purified full-length human NADK catalyzed NADP+ production from NAD+ in a coupled assay supplied with 5 mM MgATP. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The cytosolic kinase makes the phosphorylated cofactor using magnesium-associated ATP. organism: Homo sapiens tissue_or_cell_type: Purified enzyme experimental_model: Full-length recombinant human NADK; G6PD-coupled assay limitations: Scoped experimental observation; no dietary niacin or magnesium deficiency threshold or treatment benefit was tested. exposure: 5 mM MgATP; 0.1–2 mM NAD+; 1 mM additional MgCl2; 30°C cross_nutrient: Mg-ATP supplies the phosphate donor for generating niacin-derived NADP+. NADP+ production is distinct from its later reduction to NADPH. evidence_span: {"source_cache": "artifacts/niacin-redox-sources/nadk-human-2025.fulltext.txt", "locator": "Results", "start_char": 53525, "end_char": 54577, "file_sha256": "72c7b9625e1bf4137d6833adac6ae49fc108f2cd75bb4945c5b04d72a0355f9b", "text_sha256": "db49fc47ad605562e1c1cf93e1b39596505906831ae509e7ec0031485f84ba4f"} [nadk-human-2025] Cryo-EM structure and regulation of human NAD kinase. (2025). https://pubmed.ncbi.nlm.nih.gov/39854463/ DOI: 10.1126/sciadv.ads2664

cross_nutrient

Magnesium is present with ATP during phosphorylation of the niacin-derived dinucleotide; this assay does not quantify effects of dietary magnesium shortage.

evidence_span

[{"source_cache": "artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt", "locator": "Results", "start_char": 8475, "end_char": 9580, "file_sha256": "65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648", "text_sha256": "c86810a1a5342cd4e7ea126e070f28ed3182d81f17ea76c0fbb3833612c0f529"}, {"source_cache": "artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt", "locator": "Methods, NADK activity assay", "start_char": 26694, "end_char": 28732, "file_sha256": "65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648", "text_sha256": "907b651f0c0aae7a31306bdc42264cdfd22fb0e236e7ab8f37900467b0b0ab72"}]

experimental_model

Purified His-tagged Δ62C5orf33/NADK2

exposure

TLC: 5 mM NAD+, 5 mM ATP, 5 mM MgCl2; 37°C

limitations

Scoped experimental observation; no dietary niacin or magnesium deficiency threshold or treatment benefit was tested.

nutrient_topic

Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)

organism

Homo sapiens

plain_language

The mitochondrial kinase uses a phosphate-transfer reaction to create NADP+.

primary_references

[nadk2-2012] Identification and characterization of a human mitochondrial NAD kinase. (2012). https://pubmed.ncbi.nlm.nih.gov/23212377/ DOI: 10.1038/ncomms2262

tissue_or_cell_type

Purified protein

Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 871–883

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified His-tagged Δ62C5orf33/NADK2 · source_derived_draft · unverified_draft

### b3-redox-nadk2-phosphorylation Purified human NADK2 Δ62 converted NAD+ to NADP+ with ATP in MgCl2-containing reactions; TLC also detected ADP formation. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The mitochondrial kinase uses a phosphate-transfer reaction to create NADP+. organism: Homo sapiens tissue_or_cell_type: Purified protein experimental_model: Purified His-tagged Δ62C5orf33/NADK2 limitations: Scoped experimental observation; no dietary niacin or magnesium deficiency threshold or treatment benefit was tested. exposure: TLC: 5 mM NAD+, 5 mM ATP, 5 mM MgCl2; 37°C cross_nutrient: Magnesium is present with ATP during phosphorylation of the niacin-derived dinucleotide; this assay does not quantify effects of dietary magnesium shortage. evidence_span: [{"source_cache": "artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt", "locator": "Results", "start_char": 8475, "end_char": 9580, "file_sha256": "65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648", "text_sha256": "c86810a1a5342cd4e7ea126e070f28ed3182d81f17ea76c0fbb3833612c0f529"}, {"source_cache": "artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt", "locator": "Methods, NADK activity assay", "start_char": 26694, "end_char": 28732, "file_sha256": "65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648", "text_sha256": "907b651f0c0aae7a31306bdc42264cdfd22fb0e236e7ab8f37900467b0b0ab72"}] [nadk2-2012] Identification and characterization of a human mitochondrial NAD kinase. (2012). https://pubmed.ncbi.nlm.nih.gov/23212377/ DOI: 10.1038/ncomms2262

evidence_access

Primary abstract and full-text nucleotide analysis

experimental_model

Chicken muscle enzyme and nucleotide analysis.

limitations

Use ADP rather than the older inferred AMP assignment; no clinical magnesium-depletion threshold was measured.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The synthesis reaction spends ATP and produces ADP.

primary_references

Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 28–34

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Chicken muscle enzyme and nucleotide analysis. · source_derived_draft · unverified_draft

## carnosine-atp-product The synthesis reaction spends ATP and produces ADP. Purified chicken carnosine synthase formed ADP stoichiometrically during carnosine synthesis with MgATP. Model: Chicken muscle enzyme and nucleotide analysis. Limitations: Use ADP rather than the older inferred AMP assignment; no clinical magnesium-depletion threshold was measured. Evidence access: Primary abstract and full-text nucleotide analysis Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

evidence_access

Primary abstract and full-text enzyme methods

experimental_model

Human enzyme expressed in HEK293T cells.

limitations

An enzyme assay does not define dietary requirements.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Two building blocks are assembled by a specific enzyme.

primary_references

Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 20–26

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human enzyme expressed in HEK293T cells. · source_derived_draft · unverified_draft

## carnosine-synthesis Two building blocks are assembled by a specific enzyme. Purified recombinant human CARNS1 joined beta-alanine and L-histidine to form carnosine in an ATP-containing assay. Model: Human enzyme expressed in HEK293T cells. Limitations: An enzyme assay does not define dietary requirements. Evidence access: Primary abstract and full-text enzyme methods Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505