Component

Human aromatic L-amino acid decarboxylase / DDC

Human aromatic L-amino acid decarboxylase / DDC

5 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. Expressed human DDC decarboxylated L-DOPA; added PLP enhanced the measured activity.

    Human aromatic L-amino acid decarboxylase / DDC → Dopamine source_derived_draftungraded
    Experimental context and source evidence
    experimental_model
    Human DDC expressed in monkey COS cells; enzyme assays
    exposure
    PLP addition to transfected COS-cell enzyme incubations.
    limitations
    An expression-system response is not proof that supplements increase brain monoamines.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Human DDC expressed in monkey COS cells
    plain_language
    B6 cofactor supports this monoamine-producing step.
    primary_references
    [sumi-1990-ddc] Characterization of recombinant human aromatic L-amino acid decarboxylase expressed in COS cells (1990). https://doi.org/10.1111/j.1471-4159.1990.tb04601.x DOI: 10.1111/j.1471-4159.1990.tb04601.x
    tissue_or_cell_type
    COS-cell expression system

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 999–1009

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human DDC expressed in monkey COS cells; enzyme assays · source_derived_draft · unverified_draft

    ### b6-neuro-ddc-dopamine Expressed human DDC decarboxylated L-DOPA; added PLP enhanced the measured activity. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: B6 cofactor supports this monoamine-producing step. organism: Human DDC expressed in monkey COS cells tissue_or_cell_type: COS-cell expression system experimental_model: Human DDC expressed in monkey COS cells; enzyme assays limitations: An expression-system response is not proof that supplements increase brain monoamines. exposure: PLP addition to transfected COS-cell enzyme incubations. [sumi-1990-ddc] Characterization of recombinant human aromatic L-amino acid decarboxylase expressed in COS cells (1990). https://doi.org/10.1111/j.1471-4159.1990.tb04601.x DOI: 10.1111/j.1471-4159.1990.tb04601.x
    Complete structured claim and evidence

  2. Expressed human DDC decarboxylated 5-hydroxy-L-tryptophan; added PLP enhanced the measured activity.

    Human aromatic L-amino acid decarboxylase / DDC → Serotonin source_derived_draftungraded
    Experimental context and source evidence
    experimental_model
    Human DDC expressed in monkey COS cells; enzyme assays
    exposure
    PLP addition to transfected COS-cell enzyme incubations.
    limitations
    An expression-system response is not proof that supplements increase brain monoamines.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Human DDC expressed in monkey COS cells
    plain_language
    B6 cofactor supports this monoamine-producing step.
    primary_references
    [sumi-1990-ddc] Characterization of recombinant human aromatic L-amino acid decarboxylase expressed in COS cells (1990). https://doi.org/10.1111/j.1471-4159.1990.tb04601.x DOI: 10.1111/j.1471-4159.1990.tb04601.x
    tissue_or_cell_type
    COS-cell expression system

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1011–1021

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human DDC expressed in monkey COS cells; enzyme assays · source_derived_draft · unverified_draft

    ### b6-neuro-ddc-serotonin Expressed human DDC decarboxylated 5-hydroxy-L-tryptophan; added PLP enhanced the measured activity. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: B6 cofactor supports this monoamine-producing step. organism: Human DDC expressed in monkey COS cells tissue_or_cell_type: COS-cell expression system experimental_model: Human DDC expressed in monkey COS cells; enzyme assays limitations: An expression-system response is not proof that supplements increase brain monoamines. exposure: PLP addition to transfected COS-cell enzyme incubations. [sumi-1990-ddc] Characterization of recombinant human aromatic L-amino acid decarboxylase expressed in COS cells (1990). https://doi.org/10.1111/j.1471-4159.1990.tb04601.x DOI: 10.1111/j.1471-4159.1990.tb04601.x
    Complete structured claim and evidence

What acts on it

  1. Human holoDDC crystallography resolved an internal PLP aldimine at 1.9 angstrom resolution.

    PLP → Human aromatic L-amino acid decarboxylase / DDC source_derived_draftungraded
    Experimental context and source evidence
    experimental_model
    Recombinant human DDC structures, SAXS and molecular dynamics
    exposure
    Crystallized purified holoenzyme.
    limitations
    Structure describes a catalytic state, not a dietary dose requirement.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    The active B6 cofactor is chemically attached inside DDC.
    primary_references
    [bisello-2023-ddc] Human aromatic amino acid decarboxylase is an asymmetric and flexible enzyme: Implication in aromatic amino acid decarboxylase deficiency (2023). https://pmc.ncbi.nlm.nih.gov/articles/PMC10382914/ DOI: 10.1002/pro.4732
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1035–1045

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human DDC structures, SAXS and molecular dynamics · source_derived_draft · unverified_draft

    ### b6-neuro-ddc-internal-aldimine Human holoDDC crystallography resolved an internal PLP aldimine at 1.9 angstrom resolution. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The active B6 cofactor is chemically attached inside DDC. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Recombinant human DDC structures, SAXS and molecular dynamics limitations: Structure describes a catalytic state, not a dietary dose requirement. exposure: Crystallized purified holoenzyme. [bisello-2023-ddc] Human aromatic amino acid decarboxylase is an asymmetric and flexible enzyme: Implication in aromatic amino acid decarboxylase deficiency (2023). https://pmc.ncbi.nlm.nih.gov/articles/PMC10382914/ DOI: 10.1002/pro.4732
    Complete structured claim and evidence

  2. Human apoDDC has exposed active sites; PLP-titrated structures and kinetics support a cofactor-linked conformational transition.

    PLP → Human aromatic L-amino acid decarboxylase / DDC source_derived_draftungraded
    Experimental context and source evidence
    experimental_model
    Purified human DDC crystallography and kinetics
    exposure
    Apoenzyme crystallization and varied crystal PLP concentrations.
    limitations
    The closed comparison included pig holoenzyme; proposed degradation consequences were not directly established.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Cofactor binding changes the enzyme structure.
    primary_references
    [giardina-2011-ddc] Open conformation of human DOPA decarboxylase reveals the mechanism of PLP addition to Group II decarboxylases (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3251144/ DOI: 10.1073/pnas.1111456108
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1023–1033

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

    ### b6-neuro-ddc-plp-conformation Human apoDDC has exposed active sites; PLP-titrated structures and kinetics support a cofactor-linked conformational transition. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Cofactor binding changes the enzyme structure. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified human DDC crystallography and kinetics limitations: The closed comparison included pig holoenzyme; proposed degradation consequences were not directly established. exposure: Apoenzyme crystallization and varied crystal PLP concentrations. [giardina-2011-ddc] Open conformation of human DOPA decarboxylase reveals the mechanism of PLP addition to Group II decarboxylases (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3251144/ DOI: 10.1073/pnas.1111456108
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. The CYB561-deficient patients responded favorably to L-dihydroxyphenylserine, a precursor that can be converted directly to norepinephrine.

    L-Dihydroxyphenylserine / droxidopa → Human CYB561-dependent vesicular catecholamine synthesis source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_access
    Primary abstract
    experimental_model
    Reported treatment responses in a small genetic case series.
    limitations
    This is a specific drug bypass, not evidence that tyrosine or ascorbate supplements correct the defect.
    nutrient_topic
    L-Tyrosine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Tyrosine
    plain_language
    A downstream precursor can bypass a particular broken step.
    primary_references
    Mutations in CYB561 Causing a Novel Orthostatic Hypotension Syndrome. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29343526/ · DOI 10.1161/CIRCRESAHA.117.311949
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    L-Tyrosine: catecholamines, thyroid chemistry, pigment, metabolism and cross-nutrient mechanisms (2026-09-19) · lines 60–66

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Reported treatment responses in a small genetic case series. · source_derived_draft · unverified_draft

    ## l-tyrosine-cyb-bypass A downstream precursor can bypass a particular broken step. The CYB561-deficient patients responded favorably to L-dihydroxyphenylserine, a precursor that can be converted directly to norepinephrine. Model: Reported treatment responses in a small genetic case series. Limitations: This is a specific drug bypass, not evidence that tyrosine or ascorbate supplements correct the defect. Evidence access: Primary abstract Mutations in CYB561 Causing a Novel Orthostatic Hypotension Syndrome. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29343526/ · DOI 10.1161/CIRCRESAHA.117.311949
    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.

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