Component

Dopamine beta-hydroxylase catalytic turnover

Dopamine beta-hydroxylase catalytic turnover. Species, exposure and limitations are retained in each linked claim.

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 it acts on

  1. Incubation with tyramine produced a time-dependent decrease in reduced intragranular ascorbate proportional to extragranular tyramine concentration over 50 microM to 2 mM.

    Dopamine beta-hydroxylase catalytic turnover → Reduced ascorbate inside the chromaffin granule source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    nutrient_deficiency Imported condition classification; unverified.
    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
    Every molecule of noradrenaline made costs the vesicle a molecule of vitamin C.
    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
    trigger_kind
    nutrient_deficiency Imported condition classification; unverified.

    Cold water immersion: cold sensing, heat production, the catecholamine axis and what repeated exposure changes (2026-09-19) · lines 611–622

    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-depletion-in-granule Incubation with tyramine produced a time-dependent decrease in reduced intragranular ascorbate proportional to extragranular tyramine concentration over 50 microM to 2 mM. Condition category: nutrient_deficiency 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: Every molecule of noradrenaline made costs the vesicle a molecule of vitamin C. 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

What acts on it

  1. Ascorbate is the presumed in vivo reductant of dopamine beta-monooxygenase; the one-electron reductant ferrocyanide was nearly as kinetically competent, while dopamine as sole reductant reduced enzymic copper in a rate-limiting step 40-fold slower than with ascorbate, and the reductant binds at a site physically distinct from the substrate site.

    L-Ascorbate → Dopamine beta-hydroxylase catalytic turnover source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/cold-research/3676254.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e929132eed0f1c94ab0bdbef6e31bca7ecbed222cf9b585e17a1cfae7e93c82a", "start_char": 0, "end_char": 1648, "text_sha256": "e929132eed0f1c94ab0bdbef6e31bca7ecbed222cf9b585e17a1cfae7e93c82a"}
    experimental_model
    Steady-state kinetics of dopamine beta-monooxygenase with structurally distinct reductants
    exposure
    Ascorbate, ferrocyanide or dopamine itself as the reducing agent, with deuterium isotope effects
    limitations
    A kinetic comparison identifying ascorbate as the presumed physiological reductant and locating a separate binding site for it. Truncated abstract; the reductant site is inferred from kinetics and modelling.
    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 enzyme
    plain_language
    Vitamin C is what hands the enzyme back its electrons, and without it the reaction crawls.
    primary_references
    [cold-p3676254] Characterization of alternate reductant binding and electron transfer in the dopamine beta-monooxygenase reaction. (1987). https://pubmed.ncbi.nlm.nih.gov/3676254/ DOI: 10.1021/bi00391a013
    tissue_or_cell_type
    Purified enzyme

    Cold water immersion: cold sensing, heat production, the catecholamine axis and what repeated exposure changes (2026-09-19) · lines 585–596

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Steady-state kinetics of dopamine beta-monooxygenase with structurally distinct reductants · source_derived_draft · unverified_draft

    ### cold-ascorbate-reductant Ascorbate is the presumed in vivo reductant of dopamine beta-monooxygenase; the one-electron reductant ferrocyanide was nearly as kinetically competent, while dopamine as sole reductant reduced enzymic copper in a rate-limiting step 40-fold slower than with ascorbate, and the reductant binds at a site physically distinct from the substrate site. 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: Vitamin C is what hands the enzyme back its electrons, and without it the reaction crawls. organism: Bovine enzyme tissue_or_cell_type: Purified enzyme experimental_model: Steady-state kinetics of dopamine beta-monooxygenase with structurally distinct reductants limitations: A kinetic comparison identifying ascorbate as the presumed physiological reductant and locating a separate binding site for it. Truncated abstract; the reductant site is inferred from kinetics and modelling. exposure: Ascorbate, ferrocyanide or dopamine itself as the reducing agent, with deuterium isotope effects evidence_span: {"source_cache": "artifacts/cold-research/3676254.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e929132eed0f1c94ab0bdbef6e31bca7ecbed222cf9b585e17a1cfae7e93c82a", "start_char": 0, "end_char": 1648, "text_sha256": "e929132eed0f1c94ab0bdbef6e31bca7ecbed222cf9b585e17a1cfae7e93c82a"} [cold-p3676254] Characterization of alternate reductant binding and electron transfer in the dopamine beta-monooxygenase reaction. (1987). https://pubmed.ncbi.nlm.nih.gov/3676254/ DOI: 10.1021/bi00391a013
    Complete structured claim and evidence

  2. Below a ratio of eight copper atoms per tetramer, the measured rate of enzymatic catalysis rose in proportion to the copper present rather than being maximal.

    Dopamine beta-hydroxylase below its eight-copper stoichiometry → Dopamine beta-hydroxylase catalytic turnover source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    nutrient_deficiency Imported condition classification; unverified.
    evidence_span
    {"source_cache": "artifacts/cold-research/6323422.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62", "start_char": 0, "end_char": 1346, "text_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62"}
    experimental_model
    Copper titration of bovine adrenal dopamine beta-hydroxylase followed by NMR, EPR and inhibitor kinetics
    exposure
    Titration with copper and measurement of catalytic rate
    limitations
    Stoichiometry measured three independent ways. It establishes how much copper the enzyme needs, not how much copper a person needs.
    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 enzyme
    plain_language
    Short the enzyme of copper and it runs proportionally slower.
    primary_references
    [cold-p6323422] Kinetic and spectroscopic studies of the interaction of copper with dopamine beta-hydroxylase. (1984). https://pubmed.ncbi.nlm.nih.gov/6323422/ DOI: 10.1016/s0021-9258(17)43105-x
    tissue_or_cell_type
    Adrenal medulla enzyme
    trigger_kind
    nutrient_deficiency Imported condition classification; unverified.

    Cold water immersion: cold sensing, heat production, the catecholamine axis and what repeated exposure changes (2026-09-19) · lines 572–583

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Copper titration of bovine adrenal dopamine beta-hydroxylase followed by NMR, EPR and inhibitor kinetics · source_derived_draft · unverified_draft

    ### cold-copper-free-dbh-activity Below a ratio of eight copper atoms per tetramer, the measured rate of enzymatic catalysis rose in proportion to the copper present rather than being maximal. Condition category: nutrient_deficiency 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: Short the enzyme of copper and it runs proportionally slower. organism: Bovine enzyme tissue_or_cell_type: Adrenal medulla enzyme experimental_model: Copper titration of bovine adrenal dopamine beta-hydroxylase followed by NMR, EPR and inhibitor kinetics limitations: Stoichiometry measured three independent ways. It establishes how much copper the enzyme needs, not how much copper a person needs. exposure: Titration with copper and measurement of catalytic rate evidence_span: {"source_cache": "artifacts/cold-research/6323422.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62", "start_char": 0, "end_char": 1346, "text_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62"} [cold-p6323422] Kinetic and spectroscopic studies of the interaction of copper with dopamine beta-hydroxylase. (1984). https://pubmed.ncbi.nlm.nih.gov/6323422/ DOI: 10.1016/s0021-9258(17)43105-x
    Complete structured claim and evidence

  3. Dopamine beta-hydroxylase specifically binds 8 moles of copper per mole of tetramer, confirmed by radiolabel, atomic absorption, NMR and EPR titration, and catalytic rate increased with copper up to that ratio and was constant thereafter, so this stoichiometry is required for maximal activity.

    Copper → Dopamine beta-hydroxylase catalytic turnover source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/cold-research/6323422.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62", "start_char": 0, "end_char": 1346, "text_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62"}
    experimental_model
    Copper titration of bovine adrenal dopamine beta-hydroxylase followed by NMR, EPR and inhibitor kinetics
    exposure
    Titration with copper and measurement of catalytic rate
    limitations
    Stoichiometry measured three independent ways. It establishes how much copper the enzyme needs, not how much copper a person needs.
    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 enzyme
    plain_language
    The enzyme that turns dopamine into noradrenaline needs exactly eight copper atoms to work fully.
    primary_references
    [cold-p6323422] Kinetic and spectroscopic studies of the interaction of copper with dopamine beta-hydroxylase. (1984). https://pubmed.ncbi.nlm.nih.gov/6323422/ DOI: 10.1016/s0021-9258(17)43105-x
    tissue_or_cell_type
    Adrenal medulla enzyme

    Cold water immersion: cold sensing, heat production, the catecholamine axis and what repeated exposure changes (2026-09-19) · lines 559–570

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Copper titration of bovine adrenal dopamine beta-hydroxylase followed by NMR, EPR and inhibitor kinetics · source_derived_draft · unverified_draft

    ### cold-dbh-copper-stoichiometry Dopamine beta-hydroxylase specifically binds 8 moles of copper per mole of tetramer, confirmed by radiolabel, atomic absorption, NMR and EPR titration, and catalytic rate increased with copper up to that ratio and was constant thereafter, so this stoichiometry is required for maximal activity. 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 enzyme that turns dopamine into noradrenaline needs exactly eight copper atoms to work fully. organism: Bovine enzyme tissue_or_cell_type: Adrenal medulla enzyme experimental_model: Copper titration of bovine adrenal dopamine beta-hydroxylase followed by NMR, EPR and inhibitor kinetics limitations: Stoichiometry measured three independent ways. It establishes how much copper the enzyme needs, not how much copper a person needs. exposure: Titration with copper and measurement of catalytic rate evidence_span: {"source_cache": "artifacts/cold-research/6323422.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62", "start_char": 0, "end_char": 1346, "text_sha256": "dac85ce0ad7c7d5994b97d55b129050a0e7ca8bf96943578d272054db6a07a62"} [cold-p6323422] Kinetic and spectroscopic studies of the interaction of copper with dopamine beta-hydroxylase. (1984). https://pubmed.ncbi.nlm.nih.gov/6323422/ DOI: 10.1016/s0021-9258(17)43105-x
    Complete structured claim and evidence

In the sources

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

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