Component

Human eNOS catalytic activity

Human eNOS catalytic activity. Species, exposure and limitations are retained in each linked claim.

3 recorded relationships. Experimental role, claim status and evidence remain attached to each record.

Read recorded mechanisms Open recursive mind map

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What acts on it

  1. The calcium ionophore A23187 increased arginine-to-citrulline conversion in cells expressing human endothelial NOS.

    Calcium ion → Human eNOS catalytic activity source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/citrulline-research/1378832.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206", "start_char": 0, "end_char": 1652, "text_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206"}
    experimental_model
    Functional expression and reporter-cell coculture
    exposure
    NOS3 transfection and calcium ionophore A23187
    limitations
    Heterologous expression; reporter activation supports bioactive NO production, not a clinical calcium supplementation effect.
    nutrient_topic
    Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline
    organism
    Human NOS3 expressed in NIH3T3 cells; rat reporter fibroblasts
    plain_language
    Calcium signaling can activate this enzyme; this experiment did not test taking calcium tablets.
    primary_references
    [citrulline-p1378832] Cloning and expression of a cDNA encoding human endothelium-derived relaxing factor/nitric oxide synthase. (1992). https://pubmed.ncbi.nlm.nih.gov/1378832/ DOI: 10.1016/s0021-9258(18)42066-2
    tissue_or_cell_type
    Arginine conversion and NO-dependent reporter guanylate cyclase activity

    Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 476–487

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Functional expression and reporter-cell coculture · source_derived_draft · unverified_draft

    ### citrulline-calcium-nos The calcium ionophore A23187 increased arginine-to-citrulline conversion in cells expressing human endothelial NOS. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Calcium signaling can activate this enzyme; this experiment did not test taking calcium tablets. organism: Human NOS3 expressed in NIH3T3 cells; rat reporter fibroblasts tissue_or_cell_type: Arginine conversion and NO-dependent reporter guanylate cyclase activity experimental_model: Functional expression and reporter-cell coculture limitations: Heterologous expression; reporter activation supports bioactive NO production, not a clinical calcium supplementation effect. exposure: NOS3 transfection and calcium ionophore A23187 evidence_span: {"source_cache": "artifacts/citrulline-research/1378832.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206", "start_char": 0, "end_char": 1652, "text_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206"} [citrulline-p1378832] Cloning and expression of a cDNA encoding human endothelium-derived relaxing factor/nitric oxide synthase. (1992). https://pubmed.ncbi.nlm.nih.gov/1378832/ DOI: 10.1016/s0021-9258(18)42066-2
    Complete structured claim and evidence

  2. Coexpressing human calmodulin stabilized eNOS and raised its specific activity; later calmodulin addition did not reproduce the gain.

    Calmodulin → Human eNOS catalytic activity source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/citrulline-research/8951046.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb", "start_char": 0, "end_char": 1362, "text_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb"}
    experimental_model
    Recombinant coexpression and enzyme activity comparison
    exposure
    Calmodulin coexpression versus adding calmodulin after expression
    limitations
    Expression-system result; not a test of dietary calcium or calmodulin supplementation.
    nutrient_topic
    Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline
    organism
    Human NOS3 and human calmodulin expressed in E. coli
    plain_language
    How the enzyme assembles with its regulatory protein mattered.
    primary_references
    [citrulline-p8951046] Human endothelial nitric oxide synthase: expression in Escherichia coli, coexpression with calmodulin, and characterization. (1996). https://pubmed.ncbi.nlm.nih.gov/8951046/ DOI: 10.1006/abbi.1996.0543
    tissue_or_cell_type
    NOS expression and catalytic function

    Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 593–604

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

    ### citrulline-calmodulin-nos Coexpressing human calmodulin stabilized eNOS and raised its specific activity; later calmodulin addition did not reproduce the gain. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: How the enzyme assembles with its regulatory protein mattered. organism: Human NOS3 and human calmodulin expressed in E. coli tissue_or_cell_type: NOS expression and catalytic function experimental_model: Recombinant coexpression and enzyme activity comparison limitations: Expression-system result; not a test of dietary calcium or calmodulin supplementation. exposure: Calmodulin coexpression versus adding calmodulin after expression evidence_span: {"source_cache": "artifacts/citrulline-research/8951046.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb", "start_char": 0, "end_char": 1362, "text_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb"} [citrulline-p8951046] Human endothelial nitric oxide synthase: expression in Escherichia coli, coexpression with calmodulin, and characterization. (1996). https://pubmed.ncbi.nlm.nih.gov/8951046/ DOI: 10.1006/abbi.1996.0543
    Complete structured claim and evidence

  3. Purified human eNOS showed an absolute BH4 requirement for the measured catalytic reaction.

    Tetrahydrobiopterin / BH4 → Human eNOS catalytic activity source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"}
    experimental_model
    Purified recombinant enzyme activity and cofactor analysis
    exposure
    Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements
    limitations
    Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.
    nutrient_topic
    Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline
    organism
    Human NOS3 expressed in yeast
    plain_language
    Supplying substrate does not replace the required pterin cofactor.
    primary_references
    [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658
    tissue_or_cell_type
    Endothelial NOS enzyme preparation

    Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 515–526

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

    ### citrulline-nos-bh4 Purified human eNOS showed an absolute BH4 requirement for the measured catalytic reaction. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Supplying substrate does not replace the required pterin cofactor. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658
    Complete structured claim and evidence

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

    This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

    Evidence, AI assistance and curation standards