Component

Human branched-chain ketoacid dehydrogenase E1

BCKDHA/BCKDHB alpha2-beta2 E1b component; distinct from the complete BCKDH complex.

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. The human E1b coordinate model 1DTW contains two ThDP molecules and two Mg ions in its alpha2-beta2 assembly.

    Human branched-chain ketoacid dehydrogenase E1 → Mg2+ source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Magnesium and thiamine-derived ThDP intersect at mitochondrial carbon metabolism; purified-enzyme responses do not measure whole-body energy supply.
    experimental_model
    Human E1b crystallography, deposited structure 1DTW.
    limitations
    Occupancy supports cofactor architecture; clinical Mg limitation was not tested.
    nutrient_topic
    Magnesium research collection; topical membership is not evidence of a direct dietary effect. · Magnesium
    organism
    Homo sapiens
    plain_language
    The branched-chain ketoacid enzyme contains both vitamin B1-derived cofactor and magnesium.
    primary_references
    [aevarsson-2000-bckdh] Crystal structure of human branched-chain alpha-ketoacid dehydrogenase and the molecular basis of multienzyme complex deficiency in maple syrup urine disease (2000). https://pubmed.ncbi.nlm.nih.gov/10745006/ DOI: 10.1016/s0969-2126(00)00105-2
    structure_url
    https://www.ncbi.nlm.nih.gov/Structure/pdb/1DTW
    tissue_or_cell_type
    Recombinant E1b crystal

    Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 637–648

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human E1b crystallography, deposited structure 1DTW. · source_derived_draft · unverified_draft

    ### mg-bckdh-e1-cofactor-occupancy The human E1b coordinate model 1DTW contains two ThDP molecules and two Mg ions in its alpha2-beta2 assembly. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: The branched-chain ketoacid enzyme contains both vitamin B1-derived cofactor and magnesium. organism: Homo sapiens tissue_or_cell_type: Recombinant E1b crystal experimental_model: Human E1b crystallography, deposited structure 1DTW. limitations: Occupancy supports cofactor architecture; clinical Mg limitation was not tested. cross_nutrient: Magnesium and thiamine-derived ThDP intersect at mitochondrial carbon metabolism; purified-enzyme responses do not measure whole-body energy supply. structure_url: https://www.ncbi.nlm.nih.gov/Structure/pdb/1DTW [aevarsson-2000-bckdh] Crystal structure of human branched-chain alpha-ketoacid dehydrogenase and the molecular basis of multienzyme complex deficiency in maple syrup urine disease (2000). https://pubmed.ncbi.nlm.nih.gov/10745006/ DOI: 10.1016/s0969-2126(00)00105-2
    Complete structured claim and evidence

  2. Human BCKDH E1 decarboxylates a branched-chain alpha-ketoacid using ThDP and reductively acylates the lipoylated DBT domain.

    Human branched-chain ketoacid dehydrogenase E1 → Dihydrolipoyl branched-chain transacylase / DBT source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Thiamine and protein-bound lipoate connect branched-chain amino-acid catabolism; CoA and DLD act later.
    evidence
    [{"paper_key": "li-2004-bckdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}]
    experimental_model
    Recombinant human E1b and E2b lipoyl domain assays.
    limitations
    Purified-system evidence; nutritional response was not tested.
    nutrient
    Thiamine (vitamin B1) · Thiamine (vitamin B1)
    nutrient_topic
    Thiamine research collection; topical membership is not evidence of a direct dietary effect. · Thiamine (vitamin B1)
    organism
    Homo sapiens
    plain_language
    B1 helps process ketoacids formed from branched-chain amino acids; the acyl fragment then moves to a lipoyl carrier on E2.
    primary_references
    [li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200
    tissue_or_cell_type
    Purified proteins

    Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 773–785

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human E1b and E2b lipoyl domain assays. · source_derived_draft · unverified_draft

    ### b1-bckdh-ketoacid-acylation Human BCKDH E1 decarboxylates a branched-chain alpha-ketoacid using ThDP and reductively acylates the lipoylated DBT domain. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: B1 helps process ketoacids formed from branched-chain amino acids; the acyl fragment then moves to a lipoyl carrier on E2. organism: Homo sapiens tissue_or_cell_type: Purified proteins experimental_model: Recombinant human E1b and E2b lipoyl domain assays. limitations: Purified-system evidence; nutritional response was not tested. evidence: [{"paper_key": "li-2004-bckdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}] cross_nutrient: Thiamine and protein-bound lipoate connect branched-chain amino-acid catabolism; CoA and DLD act later. nutrient: Thiamine (vitamin B1) [li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200
    Complete structured claim and evidence

What acts on it

  1. Human E1b contains potassium sites, including one organizing a loop near the ThDP cofactor.

    Potassium ion → Human branched-chain ketoacid dehydrogenase E1 source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Potassium and magnesium contribute distinct sites in a thiamine-dependent branched-chain ketoacid enzyme.
    experimental_model
    Human E1b crystallography, deposited structure 1DTW.
    limitations
    A structural potassium site is not a potassium-intake response experiment.
    nutrient_topic
    Magnesium research collection; topical membership is not evidence of a direct dietary effect. · Magnesium
    organism
    Homo sapiens
    plain_language
    Potassium also helps shape this B1-dependent enzyme; the metal roles are distinct.
    primary_references
    [aevarsson-2000-bckdh] Crystal structure of human branched-chain alpha-ketoacid dehydrogenase and the molecular basis of multienzyme complex deficiency in maple syrup urine disease (2000). https://pubmed.ncbi.nlm.nih.gov/10745006/ DOI: 10.1016/s0969-2126(00)00105-2
    tissue_or_cell_type
    Recombinant E1b crystal

    Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17) · lines 650–660

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human E1b crystallography, deposited structure 1DTW. · source_derived_draft · unverified_draft

    ### mg-bckdh-potassium-site Human E1b contains potassium sites, including one organizing a loop near the ThDP cofactor. Condition category: normal nutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect. plain_language: Potassium also helps shape this B1-dependent enzyme; the metal roles are distinct. organism: Homo sapiens tissue_or_cell_type: Recombinant E1b crystal experimental_model: Human E1b crystallography, deposited structure 1DTW. limitations: A structural potassium site is not a potassium-intake response experiment. cross_nutrient: Potassium and magnesium contribute distinct sites in a thiamine-dependent branched-chain ketoacid enzyme. [aevarsson-2000-bckdh] Crystal structure of human branched-chain alpha-ketoacid dehydrogenase and the molecular basis of multienzyme complex deficiency in maple syrup urine disease (2000). https://pubmed.ncbi.nlm.nih.gov/10745006/ DOI: 10.1016/s0969-2126(00)00105-2
    Complete structured claim and evidence

  2. ThDP reduced kinase-mediated phosphorylation of wild-type human E1b; loop-network mutations abolished this protection in the reconstituted assay.

    Thiamine diphosphate → Human branched-chain ketoacid dehydrogenase E1 source_derived_draftungraded
    Experimental context and source evidence
    evidence
    [{"paper_key": "li-2004-bckdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}]
    experimental_model
    Human E1b/E2b with recombinant rat BCKD kinase.
    limitations
    Mixed-species assay; kinase accessibility, not clinical thiamine responsiveness.
    nutrient
    Thiamine (vitamin B1) · Thiamine (vitamin B1)
    nutrient_topic
    Thiamine research collection; topical membership is not evidence of a direct dietary effect. · Thiamine (vitamin B1)
    organism
    Homo sapiens E1/E2; Rattus norvegicus kinase
    plain_language
    Cofactor occupancy also affected access to a regulatory site. The result depends on an intact loop and does not show that every genetic BCKDH defect responds to B1.
    primary_references
    [li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200
    tissue_or_cell_type
    Purified mixed-species assay

    Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 801–812

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human E1b/E2b with recombinant rat BCKD kinase. · source_derived_draft · unverified_draft

    ### b1-bckdh-cofactor-limits-phosphorylation ThDP reduced kinase-mediated phosphorylation of wild-type human E1b; loop-network mutations abolished this protection in the reconstituted assay. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: Cofactor occupancy also affected access to a regulatory site. The result depends on an intact loop and does not show that every genetic BCKDH defect responds to B1. organism: Homo sapiens E1/E2; Rattus norvegicus kinase tissue_or_cell_type: Purified mixed-species assay experimental_model: Human E1b/E2b with recombinant rat BCKD kinase. limitations: Mixed-species assay; kinase accessibility, not clinical thiamine responsiveness. evidence: [{"paper_key": "li-2004-bckdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}] nutrient: Thiamine (vitamin B1) [li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200
    Complete structured claim and evidence

  3. Apo/holo human E1b structures showed that ThDP binding orders the phosphorylation loop needed to recognize the lipoylated E2b domain.

    Thiamine diphosphate → Human branched-chain ketoacid dehydrogenase E1 source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    ThDP occupancy enables interaction with the lipoylated E2 carrier.
    evidence
    [{"paper_key": "li-2004-bckdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}]
    experimental_model
    Human apo/holo E1b crystallography and lipoyl-domain binding.
    limitations
    Preparation-specific structural/kinetic mechanism; not a human thiamine-dose response.
    nutrient
    Thiamine (vitamin B1) · Thiamine (vitamin B1)
    nutrient_topic
    Thiamine research collection; topical membership is not evidence of a direct dietary effect. · Thiamine (vitamin B1)
    organism
    Homo sapiens
    plain_language
    B1 binding changes the enzyme shape so it can receive its lipoyl partner.
    primary_references
    [li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200
    tissue_or_cell_type
    Purified proteins

    Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 787–799

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human apo/holo E1b crystallography and lipoyl-domain binding. · source_derived_draft · unverified_draft

    ### b1-bckdh-thdp-orders-loop Apo/holo human E1b structures showed that ThDP binding orders the phosphorylation loop needed to recognize the lipoylated E2b domain. Condition category: normal nutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect. plain_language: B1 binding changes the enzyme shape so it can receive its lipoyl partner. organism: Homo sapiens tissue_or_cell_type: Purified proteins experimental_model: Human apo/holo E1b crystallography and lipoyl-domain binding. limitations: Preparation-specific structural/kinetic mechanism; not a human thiamine-dose response. evidence: [{"paper_key": "li-2004-bckdh", "source_bundle": "artifacts/thiamine_metabolism_sources.json", "passage_ids": ["abstract"], "locator": "Primary publication abstract", "preservation": "Exact text retained in the source bundle; full source document retained when openly retrievable."}] cross_nutrient: ThDP occupancy enables interaction with the lipoylated E2 carrier. nutrient: Thiamine (vitamin B1) [li-2004-bckdh] Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase (2004). https://pubmed.ncbi.nlm.nih.gov/15166214/ DOI: 10.1074/jbc.m403611200
    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