Delta-1-pyrroline-5-carboxylate / P5C

evidence_access

Primary abstract

experimental_model

Cell-free NMR, chromatography and mass-spectrometry experiments motivated by hyperprolinemia type II.

limitations

This demonstrates chemistry under the tested conditions, not B6 depletion from an ordinary proline-containing meal.

nutrient_topic

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

plain_language

An accumulating proline intermediate can chemically trap active vitamin B6.

primary_references

Pyridoxal phosphate de-activation by pyrroline-5-carboxylic acid. Increased risk of vitamin B6 deficiency and seizures in hyperprolinemia type II. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11134058/ · DOI 10.1074/jbc.M010860200

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 118–124

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Cell-free NMR, chromatography and mass-spectrometry experiments motivated by hyperprolinemia type II. · source_derived_draft · unverified_draft

## l-proline-p5c-b6-trapping An accumulating proline intermediate can chemically trap active vitamin B6. P5C reacted with pyridoxal phosphate at pH 7.4 and 310 K to form three characterized adducts through condensation involving the PLP aldehyde group. Model: Cell-free NMR, chromatography and mass-spectrometry experiments motivated by hyperprolinemia type II. Limitations: This demonstrates chemistry under the tested conditions, not B6 depletion from an ordinary proline-containing meal. Evidence access: Primary abstract Pyridoxal phosphate de-activation by pyrroline-5-carboxylic acid. Increased risk of vitamin B6 deficiency and seizures in hyperprolinemia type II. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11134058/ · DOI 10.1074/jbc.M010860200

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Human index-case context combined with in-vitro chemical mechanism.

limitations

Contribution to seizures is an interpretation; the paper does not establish controlled efficacy or a universal treatment dose.

nutrient_topic

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

plain_language

A breakdown disorder can create a secondary cofactor problem.

primary_references

Pyridoxal phosphate de-activation by pyrroline-5-carboxylic acid. Increased risk of vitamin B6 deficiency and seizures in hyperprolinemia type II. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11134058/ · DOI 10.1074/jbc.M010860200

trigger_kind

machinery_impairment Imported condition classification; unverified.

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 126–132

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human index-case context combined with in-vitro chemical mechanism. · source_derived_draft · unverified_draft

## l-proline-p5c-clinical-link A breakdown disorder can create a secondary cofactor problem. The study was prompted by B6 deficiency and seizures in a child with hyperprolinemia type II; the adduct experiments support P5C-mediated cofactor inactivation as a contributing mechanism. Model: Human index-case context combined with in-vitro chemical mechanism. Limitations: Contribution to seizures is an interpretation; the paper does not establish controlled efficacy or a universal treatment dose. Evidence access: Primary abstract Pyridoxal phosphate de-activation by pyrroline-5-carboxylic acid. Increased risk of vitamin B6 deficiency and seizures in hyperprolinemia type II. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11134058/ · DOI 10.1074/jbc.M010860200

evidence_access

Primary full text; background reaction distinguished from new experiments

experimental_model

Established reaction described in a primary mitochondrial proline-oxidation study.

limitations

The reaction description is biochemical background, distinct from the paper-specific ROS-site experiments.

nutrient_topic

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

plain_language

Breaking proline down starts with a flavin-dependent mitochondrial enzyme.

primary_references

Sources of superoxide/H2O2 during mitochondrial proline oxidation. · 2014 · https://pubmed.ncbi.nlm.nih.gov/25184115/ · DOI 10.1016/j.redox.2014.07.003

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 94–100

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Established reaction described in a primary mitochondrial proline-oxidation study. · source_derived_draft · unverified_draft

## l-proline-prodh-oxidation Breaking proline down starts with a flavin-dependent mitochondrial enzyme. Mitochondrial PRODH catalyzes the FAD-dependent oxidation of proline to P5C, linking proline breakdown to mitochondrial electron transfer. Model: Established reaction described in a primary mitochondrial proline-oxidation study. Limitations: The reaction description is biochemical background, distinct from the paper-specific ROS-site experiments. Evidence access: Primary full text; background reaction distinguished from new experiments Sources of superoxide/H2O2 during mitochondrial proline oxidation. · 2014 · https://pubmed.ncbi.nlm.nih.gov/25184115/ · DOI 10.1016/j.redox.2014.07.003

evidence_span

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experimental_model

Patient genetics and recombinant variant expression

exposure

ALDH18A1 R84Q compared with wild-type isoforms

limitations

Rare inherited enzyme disorder; does not imply low dietary citrulline caused the clinical phenotype.

nutrient_topic

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

organism

Human, two siblings and mammalian expression systems

plain_language

This supplies a precursor route connected to ornithine and arginine production.

primary_references

[citrulline-p11092761] Hyperammonemia with reduced ornithine, citrulline, arginine and proline: a new inborn error caused by a mutation in the gene encoding delta(1)-pyrroline-5-carboxylate synthase. (2000). https://pubmed.ncbi.nlm.nih.gov/11092761/ DOI: 10.1093/hmg/9.19.2853

tissue_or_cell_type

Mitochondrial P5CS and circulating amino acids

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 294–305

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Patient genetics and recombinant variant expression · source_derived_draft · unverified_draft

### citrulline-p5cs-reaction Human P5CS links glutamate to P5C synthesis through ATP- and NADPH-dependent chemistry. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: This supplies a precursor route connected to ornithine and arginine production. organism: Human, two siblings and mammalian expression systems tissue_or_cell_type: Mitochondrial P5CS and circulating amino acids experimental_model: Patient genetics and recombinant variant expression limitations: Rare inherited enzyme disorder; does not imply low dietary citrulline caused the clinical phenotype. exposure: ALDH18A1 R84Q compared with wild-type isoforms evidence_span: {"source_cache": "artifacts/citrulline-research/11092761.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "09706fd9ec135c472473decaa612e06b3e5aa021c9b1493d77daf4fe98b8d5d2", "start_char": 0, "end_char": 1688, "text_sha256": "09706fd9ec135c472473decaa612e06b3e5aa021c9b1493d77daf4fe98b8d5d2"} [citrulline-p11092761] Hyperammonemia with reduced ornithine, citrulline, arginine and proline: a new inborn error caused by a mutation in the gene encoding delta(1)-pyrroline-5-carboxylate synthase. (2000). https://pubmed.ncbi.nlm.nih.gov/11092761/ DOI: 10.1093/hmg/9.19.2853

evidence_access

Primary abstract

experimental_model

Reaction chemistry described in the human OAT study.

limitations

This step alone does not demonstrate arginine supplementation improves collagen deposition.

nutrient_topic

L-Arginine collection; tissue, species, dose and formulation distinctions retained. · L-Arginine

plain_language

A separate chemical step links the reaction products.

primary_references

Crystal structure of human recombinant ornithine aminotransferase. · 1998 · https://pubmed.ncbi.nlm.nih.gov/9514741/ · DOI 10.1006/jmbi.1997.1583

L-Arginine: transport, metabolic branches, nutrient interactions, availability and discovery questions (2026-09-18) · lines 126–132

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Reaction chemistry described in the human OAT study. · source_derived_draft · unverified_draft

## arg-p5c A separate chemical step links the reaction products. Glutamate-5-semialdehyde spontaneously cyclizes to P5C. Model: Reaction chemistry described in the human OAT study. Limitations: This step alone does not demonstrate arginine supplementation improves collagen deposition. Evidence access: Primary abstract Crystal structure of human recombinant ornithine aminotransferase. · 1998 · https://pubmed.ncbi.nlm.nih.gov/9514741/ · DOI 10.1006/jmbi.1997.1583

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Recombinant human mutant/wild-type structures and kinetic analysis.

limitations

This tests one inherited variant and does not establish a nutrient-addition rescue.

nutrient_topic

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

plain_language

A structural defect can block proline breakdown even when substrate is plentiful.

primary_references

The three-dimensional structural basis of type II hyperprolinemia. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22516612/ · DOI 10.1016/j.jmb.2012.04.010

trigger_kind

machinery_impairment Imported condition classification; unverified.

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 110–116

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Recombinant human mutant/wild-type structures and kinetic analysis. · source_derived_draft · unverified_draft

## l-proline-aldh4-failure A structural defect can block proline breakdown even when substrate is plentiful. The human ALDH4A1 S352L disease-associated variant abolished catalytic activity and NAD+ binding, with a major rearrangement of the catalytic loop. Model: Recombinant human mutant/wild-type structures and kinetic analysis. Limitations: This tests one inherited variant and does not establish a nutrient-addition rescue. Evidence access: Primary abstract The three-dimensional structural basis of type II hyperprolinemia. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22516612/ · DOI 10.1016/j.jmb.2012.04.010

evidence_access

Primary abstract

experimental_model

Human enzyme structures and kinetics; mouse enzyme complexes supplied high-resolution ligand views.

limitations

P5C and glutamate semialdehyde interconvert; the aldehyde is the oxidation substrate. Mouse ligand structures are not relabeled as human complexes.

nutrient_topic

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

plain_language

A second enzyme turns the breakdown intermediate into glutamate.

primary_references

The three-dimensional structural basis of type II hyperprolinemia. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22516612/ · DOI 10.1016/j.jmb.2012.04.010

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 102–108

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human enzyme structures and kinetics; mouse enzyme complexes supplied high-resolution ligand views. · source_derived_draft · unverified_draft

## l-proline-aldh4-oxidation A second enzyme turns the breakdown intermediate into glutamate. ALDH4A1 catalyzes NAD+-dependent oxidation of glutamate semialdehyde to glutamate, completing the second enzymatic stage of proline catabolism. Model: Human enzyme structures and kinetics; mouse enzyme complexes supplied high-resolution ligand views. Limitations: P5C and glutamate semialdehyde interconvert; the aldehyde is the oxidation substrate. Mouse ligand structures are not relabeled as human complexes. Evidence access: Primary abstract The three-dimensional structural basis of type II hyperprolinemia. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22516612/ · DOI 10.1016/j.jmb.2012.04.010

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Mammalian NADK2-deletion cell models; primary abstract.

limitations

Detailed model and exposure differences remain distinct; the two publications are not duplicate evidence records from one experiment.

nutrient_topic

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

plain_language

A second research group found the same synthesis vulnerability.

primary_references

Mitochondrial NADP+ is essential for proline biosynthesis during cell growth. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33833463/ · DOI 10.1038/s42255-021-00374-y

trigger_kind

machinery_impairment Imported condition classification; unverified.

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 78–84

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Mammalian NADK2-deletion cell models; primary abstract. · source_derived_draft · unverified_draft

## l-proline-nadk2-independent-study A second research group found the same synthesis vulnerability. A separate study found NADK2 loss depleted mitochondrial NADPH, limited P5C generation and made tested mammalian cells dependent on exogenous proline for growth. Model: Mammalian NADK2-deletion cell models; primary abstract. Limitations: Detailed model and exposure differences remain distinct; the two publications are not duplicate evidence records from one experiment. Evidence access: Primary abstract Mitochondrial NADP+ is essential for proline biosynthesis during cell growth. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33833463/ · DOI 10.1038/s42255-021-00374-y

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary full text

experimental_model

Human cell deletion, isotope tracing and rescue experiments.

limitations

The limiting step was cofactor-dependent synthesis, not a demonstrated lack of glutamine in the diet.

nutrient_topic

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

plain_language

Proline production needs reducing power in the right compartment.

primary_references

Mitochondrial NADP(H) generation is essential for proline biosynthesis. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33888598/ · DOI 10.1126/science.abd5491

trigger_kind

machinery_impairment Imported condition classification; unverified.

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 62–68

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human cell deletion, isotope tracing and rescue experiments. · source_derived_draft · unverified_draft

## l-proline-nadk2-proline Proline production needs reducing power in the right compartment. NADK2 deletion reduced glutamine-derived proline synthesis; mitochondrial NADP(H) was needed for the P5CS step reducing glutamate toward P5C. Model: Human cell deletion, isotope tracing and rescue experiments. Limitations: The limiting step was cofactor-dependent synthesis, not a demonstrated lack of glutamine in the diet. Evidence access: Primary full text Mitochondrial NADP(H) generation is essential for proline biosynthesis. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33888598/ · DOI 10.1126/science.abd5491

evidence_access

Primary full text

experimental_model

Lu1205 cells; 1 mM labeled precursors for eight hours; ornithine labeling required omission of extracellular proline.

limitations

The ornithine experiment used conditions the authors regarded as likely nonphysiological; no universal exclusive routing rule is inferred.

nutrient_topic

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

plain_language

Two precursor routes can feed the same product through differently placed enzymes.

primary_references

Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 38–44

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Lu1205 cells; 1 mM labeled precursors for eight hours; ornithine labeling required omission of extracellular proline. · source_derived_draft · unverified_draft

## l-proline-precursor-routing Two precursor routes can feed the same product through differently placed enzymes. Isotope tracing with gene silencing linked glutamine/glutamate-derived proline mainly to PYCR1/PYCR2 and ornithine-derived proline mainly to PYCRL in human melanoma cells. Model: Lu1205 cells; 1 mM labeled precursors for eight hours; ornithine labeling required omission of extracellular proline. Limitations: The ornithine experiment used conditions the authors regarded as likely nonphysiological; no universal exclusive routing rule is inferred. Evidence access: Primary full text Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

evidence_access

Primary full text

experimental_model

Human cancer-cell hypoxia experiments and three-dimensional/xenograft models.

limitations

A benefit to tumor-cell survival is not a health benefit of supplementation; proline production is part of the reaction that consumes NADH.

nutrient_topic

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

plain_language

Making proline can also help rebalance mitochondrial reducing power.

primary_references

Proline synthesis through PYCR1 is required to support cancer cell proliferation and survival in oxygen-limiting conditions. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35108535/ · DOI 10.1016/j.celrep.2022.110320

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 350–356

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human cancer-cell hypoxia experiments and three-dimensional/xenograft models. · source_derived_draft · unverified_draft

## l-proline-pycr1-hypoxic-redox Making proline can also help rebalance mitochondrial reducing power. In hypoxic cancer models, increased PYCR1-dependent proline synthesis oxidized NADH and helped sustain TCA-cycle activity. Model: Human cancer-cell hypoxia experiments and three-dimensional/xenograft models. Limitations: A benefit to tumor-cell survival is not a health benefit of supplementation; proline production is part of the reaction that consumes NADH. Evidence access: Primary full text Proline synthesis through PYCR1 is required to support cancer cell proliferation and survival in oxygen-limiting conditions. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35108535/ · DOI 10.1016/j.celrep.2022.110320

evidence_access

Primary full text

experimental_model

Purified human enzyme; comparison with 0.1 mM P5C and 0.1 mM reduced cofactor, 37 degrees C.

limitations

Cofactor preference depends on assay conditions and does not make the alternative cofactor unusable.

nutrient_topic

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

plain_language

One mitochondrial enzyme finishes the synthesis of proline.

primary_references

Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 14–20

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified human enzyme; comparison with 0.1 mM P5C and 0.1 mM reduced cofactor, 37 degrees C. · source_derived_draft · unverified_draft

## l-proline-pycr1-reduction One mitochondrial enzyme finishes the synthesis of proline. Recombinant human PYCR1 reduced P5C to proline with NADH or NADPH; in the tested conditions its specific activity was higher with NADH. Model: Purified human enzyme; comparison with 0.1 mM P5C and 0.1 mM reduced cofactor, 37 degrees C. Limitations: Cofactor preference depends on assay conditions and does not make the alternative cofactor unusable. Evidence access: Primary full text Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

evidence_access

Primary full text

experimental_model

Purified human PYCR2 and human melanoma-cell localization experiments.

limitations

PYCR2 has its own identity and disease associations; it is not interchangeable with PYCR1.

nutrient_topic

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

plain_language

A second mitochondrial enzyme performs the final reduction.

primary_references

Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 22–28

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified human PYCR2 and human melanoma-cell localization experiments. · source_derived_draft · unverified_draft

## l-proline-pycr2-reduction A second mitochondrial enzyme performs the final reduction. Recombinant human PYCR2 reduced P5C to proline and favored NADH over NADPH under the reported comparison conditions. Model: Purified human PYCR2 and human melanoma-cell localization experiments. Limitations: PYCR2 has its own identity and disease associations; it is not interchangeable with PYCR1. Evidence access: Primary full text Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

evidence_access

Primary full text

experimental_model

Lu1205 cell fractionation and recombinant human PYCRL kinetics.

limitations

The melanoma routing pattern is not asserted to apply identically in every human tissue.

nutrient_topic

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

plain_language

The cytosolic version has different preferences from the mitochondrial enzymes.

primary_references

Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

L-Proline: synthesis, collagen processing, redox metabolism and cross-nutrient mechanisms (2026-09-19) · lines 30–36

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Lu1205 cell fractionation and recombinant human PYCRL kinetics. · source_derived_draft · unverified_draft

## l-proline-pycr3-reduction The cytosolic version has different preferences from the mitochondrial enzymes. Human PYCRL/PYCR3 localized predominantly to the cytosol in the tested melanoma cells and was more efficient with NADPH in the biochemical comparison. Model: Lu1205 cell fractionation and recombinant human PYCRL kinetics. Limitations: The melanoma routing pattern is not asserted to apply identically in every human tissue. Evidence access: Primary full text Functional specialization in proline biosynthesis of melanoma. · 2012 · https://pubmed.ncbi.nlm.nih.gov/23024808/ · DOI 10.1371/journal.pone.0045190

evidence_span

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experimental_model

Recombinant enzyme crystal structure

exposure

PLP-bound enzyme structure

limitations

The described reaction direction is ornithine transamination; this structure alone does not quantify reverse flux in human intestine.

nutrient_topic

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

organism

Human OAT

plain_language

Vitamin B6 has a defined role in the machinery handling ornithine.

primary_references

[citrulline-p9514741] Crystal structure of human recombinant ornithine aminotransferase. (1998). https://pubmed.ncbi.nlm.nih.gov/9514741/ DOI: 10.1006/jmbi.1997.1583

tissue_or_cell_type

Mitochondrial ornithine transamination

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 333–344

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant enzyme crystal structure · source_derived_draft · unverified_draft

### citrulline-oat-plp Human OAT bound pyridoxal phosphate through a Schiff base to Lys292. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Vitamin B6 has a defined role in the machinery handling ornithine. organism: Human OAT tissue_or_cell_type: Mitochondrial ornithine transamination experimental_model: Recombinant enzyme crystal structure limitations: The described reaction direction is ornithine transamination; this structure alone does not quantify reverse flux in human intestine. exposure: PLP-bound enzyme structure evidence_span: {"source_cache": "artifacts/citrulline-research/9514741.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "cca17abd35f0211a043dd3cc8883369e230209206ff62b62242197f90201cea0", "start_char": 0, "end_char": 2979, "text_sha256": "cca17abd35f0211a043dd3cc8883369e230209206ff62b62242197f90201cea0"} [citrulline-p9514741] Crystal structure of human recombinant ornithine aminotransferase. (1998). https://pubmed.ncbi.nlm.nih.gov/9514741/ DOI: 10.1006/jmbi.1997.1583

evidence_span

{"source_cache": "artifacts/citrulline-research/9514741.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "cca17abd35f0211a043dd3cc8883369e230209206ff62b62242197f90201cea0", "start_char": 0, "end_char": 2979, "text_sha256": "cca17abd35f0211a043dd3cc8883369e230209206ff62b62242197f90201cea0"}

experimental_model

Recombinant enzyme crystal structure

exposure

PLP-bound enzyme structure

limitations

The described reaction direction is ornithine transamination; this structure alone does not quantify reverse flux in human intestine.

nutrient_topic

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

organism

Human OAT

plain_language

This is an ornithine-processing reaction; its direction depends on the biological setting.

primary_references

[citrulline-p9514741] Crystal structure of human recombinant ornithine aminotransferase. (1998). https://pubmed.ncbi.nlm.nih.gov/9514741/ DOI: 10.1006/jmbi.1997.1583

tissue_or_cell_type

Mitochondrial ornithine transamination

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 346–357

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant enzyme crystal structure · source_derived_draft · unverified_draft

### citrulline-oat-reaction OAT transfers the ornithine delta-amino group to 2-oxoglutarate, yielding glutamate and glutamate semialdehyde, which cyclizes to P5C. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: This is an ornithine-processing reaction; its direction depends on the biological setting. organism: Human OAT tissue_or_cell_type: Mitochondrial ornithine transamination experimental_model: Recombinant enzyme crystal structure limitations: The described reaction direction is ornithine transamination; this structure alone does not quantify reverse flux in human intestine. exposure: PLP-bound enzyme structure evidence_span: {"source_cache": "artifacts/citrulline-research/9514741.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "cca17abd35f0211a043dd3cc8883369e230209206ff62b62242197f90201cea0", "start_char": 0, "end_char": 2979, "text_sha256": "cca17abd35f0211a043dd3cc8883369e230209206ff62b62242197f90201cea0"} [citrulline-p9514741] Crystal structure of human recombinant ornithine aminotransferase. (1998). https://pubmed.ncbi.nlm.nih.gov/9514741/ DOI: 10.1006/jmbi.1997.1583