Component

Tyramine

Experimental DBH substrate; not identical to physiological dopamine.

4 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. Gut bacterial tyrosine decarboxylase accepts tyrosine and also decarboxylates levodopa.

    Enterococcus faecalis tyrosine decarboxylase → Tyramine source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Gut bacterial enzyme/substrate characterization.
    limitations
    This is bacterial metabolism, distinct from human DDC. Tyramine exposure from food is not equivalent to free tyrosine intake.
    nutrient_topic
    L-Tyrosine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Tyrosine
    plain_language
    Microbes can divert the amino acid into a bioactive amine.
    primary_references
    Gut bacterial tyrosine decarboxylases restrict levels of levodopa in the treatment of Parkinson's disease. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30659181/ · DOI 10.1038/s41467-019-08294-y

    L-Tyrosine: catecholamines, thyroid chemistry, pigment, metabolism and cross-nutrient mechanisms (2026-09-19) · lines 332–338

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Gut bacterial enzyme/substrate characterization. · source_derived_draft · unverified_draft

    ## l-tyrosine-bacterial-tyramine Microbes can divert the amino acid into a bioactive amine. Gut bacterial tyrosine decarboxylase accepts tyrosine and also decarboxylates levodopa. Model: Gut bacterial enzyme/substrate characterization. Limitations: This is bacterial metabolism, distinct from human DDC. Tyramine exposure from food is not equivalent to free tyrosine intake. Evidence access: Primary abstract Gut bacterial tyrosine decarboxylases restrict levels of levodopa in the treatment of Parkinson's disease. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30659181/ · DOI 10.1038/s41467-019-08294-y
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Bacterial tyrosine decarboxylases converted levodopa to dopamine despite competing tyrosine or human decarboxylase inhibitors.

    Enterococcus faecalis tyrosine decarboxylase → L-3,4-Dihydroxyphenylalanine source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Bacterial enzyme experiments, human PD associations and proximal-intestinal rat studies.
    limitations
    Patient abundance associations and rat plasma effects are not proof that changing dietary tyrosine improves levodopa response.
    nutrient_topic
    L-Tyrosine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Tyrosine
    plain_language
    Blocking the human enzyme may leave a microbial route active.
    primary_references
    Gut bacterial tyrosine decarboxylases restrict levels of levodopa in the treatment of Parkinson's disease. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30659181/ · DOI 10.1038/s41467-019-08294-y

    L-Tyrosine: catecholamines, thyroid chemistry, pigment, metabolism and cross-nutrient mechanisms (2026-09-19) · lines 340–346

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Bacterial enzyme experiments, human PD associations and proximal-intestinal rat studies. · source_derived_draft · unverified_draft

    ## l-tyrosine-bacterial-drug Blocking the human enzyme may leave a microbial route active. Bacterial tyrosine decarboxylases converted levodopa to dopamine despite competing tyrosine or human decarboxylase inhibitors. Model: Bacterial enzyme experiments, human PD associations and proximal-intestinal rat studies. Limitations: Patient abundance associations and rat plasma effects are not proof that changing dietary tyrosine improves levodopa response. Evidence access: Primary abstract Gut bacterial tyrosine decarboxylases restrict levels of levodopa in the treatment of Parkinson's disease. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30659181/ · DOI 10.1038/s41467-019-08294-y
    Complete structured claim and evidence

  2. Chromaffin granules must shuttle reducing equivalents inward to re-reduce ascorbate oxidised during noradrenaline synthesis: tyramine-driven turnover oxidised intragranular ascorbate with a stoichiometry of octopamine synthesised to ascorbate oxidised near unity, 95% inhibited by the enzyme inhibitor disulfiram, and abolished or reversed by extragranular ascorbate, while labelled ascorbate showed no transmembrane transport of the vitamin itself.

    Cytosolic ascorbate pool → Reduced ascorbate inside the chromaffin granule source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/cold-research/3949732.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9db1233389aeb375adfd655ea04f39ccb05e22773f367aaa1292bb21698242e1", "start_char": 0, "end_char": 2000, "text_sha256": "9db1233389aeb375adfd655ea04f39ccb05e22773f367aaa1292bb21698242e1"}
    experimental_model
    Intact bovine chromaffin granules undergoing dopamine beta-hydroxylase turnover with labelled ascorbate
    exposure
    Tyramine- or dopamine-stimulated turnover with extragranular ascorbate
    limitations
    An in vitro demonstration in intact granules. Ascorbate itself does not cross the membrane, which is precisely why a shuttle is required.
    nutrient_topic
    Cold water immersion research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Cold water immersion
    organism
    Bovine
    plain_language
    The vitamin cannot cross into the vesicle, so the cell passes electrons across the membrane instead.
    primary_references
    [cold-p3949732] Evidence for an ascorbate shuttle for the transfer of reducing equivalents across chromaffin granule membranes. (1986). https://pubmed.ncbi.nlm.nih.gov/3949732/ DOI: 10.1016/s0021-9258(17)35819-2
    tissue_or_cell_type
    Adrenal chromaffin granules

    Cold water immersion: cold sensing, heat production, the catecholamine axis and what repeated exposure changes (2026-09-19) · lines 598–609

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Intact bovine chromaffin granules undergoing dopamine beta-hydroxylase turnover with labelled ascorbate · source_derived_draft · unverified_draft

    ### cold-ascorbate-shuttle Chromaffin granules must shuttle reducing equivalents inward to re-reduce ascorbate oxidised during noradrenaline synthesis: tyramine-driven turnover oxidised intragranular ascorbate with a stoichiometry of octopamine synthesised to ascorbate oxidised near unity, 95% inhibited by the enzyme inhibitor disulfiram, and abolished or reversed by extragranular ascorbate, while labelled ascorbate showed no transmembrane transport of the vitamin itself. Condition category: normal nutrient_topic: Cold water immersion research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: The vitamin cannot cross into the vesicle, so the cell passes electrons across the membrane instead. organism: Bovine tissue_or_cell_type: Adrenal chromaffin granules experimental_model: Intact bovine chromaffin granules undergoing dopamine beta-hydroxylase turnover with labelled ascorbate limitations: An in vitro demonstration in intact granules. Ascorbate itself does not cross the membrane, which is precisely why a shuttle is required. exposure: Tyramine- or dopamine-stimulated turnover with extragranular ascorbate evidence_span: {"source_cache": "artifacts/cold-research/3949732.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9db1233389aeb375adfd655ea04f39ccb05e22773f367aaa1292bb21698242e1", "start_char": 0, "end_char": 2000, "text_sha256": "9db1233389aeb375adfd655ea04f39ccb05e22773f367aaa1292bb21698242e1"} [cold-p3949732] Evidence for an ascorbate shuttle for the transfer of reducing equivalents across chromaffin granule membranes. (1986). https://pubmed.ncbi.nlm.nih.gov/3949732/ DOI: 10.1016/s0021-9258(17)35819-2
    Complete structured claim and evidence

  3. Coupling bovine DBH tyramine hydroxylation to semidehydroascorbate reductase identified semidehydroascorbate as the immediate enzymic oxidation product of ascorbate.

    L-Ascorbate → Ascorbyl radical source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.
    experimental_model
    Purified bovine DBH coupled to rat-liver or Neurospora semidehydroascorbate reductase
    exposure
    Tyramine beta-hydroxylation with ascorbate; coupled pyridine-nucleotide oxidation and radical recycling assays.
    limitations
    Heterologous reductase-coupled assay; radical dismutation can subsequently produce DHA, so immediate product and net redox balance must be distinguished.
    nutrient_topic
    Vitamin C research collection; topical membership is not evidence of a direct dietary effect. · Vitamin C
    organism
    Bos taurus; Rattus norvegicus; Neurospora crassa
    plain_language
    This copper enzyme takes single electrons from vitamin C, leaving an ascorbyl radical that can be recycled.
    primary_references
    [dbh1981] Mechanism of dopamine-beta-hydroxylation. Semidehydroascorbate as the enzyme oxidation product of ascorbate. (1981). https://pubmed.ncbi.nlm.nih.gov/6451628/ DOI: 10.1016/S0021-9258(19)69620-1
    tissue_or_cell_type
    Bovine adrenal-medullary enzyme plus heterologous reductase preparations

    Vitamin C: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 807–818

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified bovine DBH coupled to rat-liver or Neurospora semidehydroascorbate reductase · source_derived_draft · unverified_draft

    ### vc-enzyme-dbh-radical-product Coupling bovine DBH tyramine hydroxylation to semidehydroascorbate reductase identified semidehydroascorbate as the immediate enzymic oxidation product of ascorbate. Condition category: normal nutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect. plain_language: This copper enzyme takes single electrons from vitamin C, leaving an ascorbyl radical that can be recycled. organism: Bos taurus; Rattus norvegicus; Neurospora crassa tissue_or_cell_type: Bovine adrenal-medullary enzyme plus heterologous reductase preparations experimental_model: Purified bovine DBH coupled to rat-liver or Neurospora semidehydroascorbate reductase limitations: Heterologous reductase-coupled assay; radical dismutation can subsequently produce DHA, so immediate product and net redox balance must be distinguished. cross_nutrient: Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing. exposure: Tyramine beta-hydroxylation with ascorbate; coupled pyridine-nucleotide oxidation and radical recycling assays. [dbh1981] Mechanism of dopamine-beta-hydroxylation. Semidehydroascorbate as the enzyme oxidation product of ascorbate. (1981). https://pubmed.ncbi.nlm.nih.gov/6451628/ DOI: 10.1016/S0021-9258(19)69620-1
    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