{"id":"7a76d751-70f3-5f63-96e2-b4f73496d059","stable_key":"0f17db03-207f-5910-ac8e-13dfc2f378ce:mg-bckdh-e1-cofactor-occupancy","predicate":"binds","statement":"The human E1b coordinate model 1DTW contains two ThDP molecules and two Mg ions in its alpha2-beta2 assembly.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"dce0e7fe-db4f-5b9b-9dfb-72590659886f","mechanism_event_label":"The branched-chain ketoacid enzyme contains both vitamin B1-derived cofactor and magnesium.","subject":{"id":"82b74ccc-3ee5-5622-a8bd-0691de8cdc54","slug":"bckdh-e1","display_name":"Human branched-chain ketoacid dehydrogenase E1","entity_type_key":"protein_complex"},"object":{"id":"bff427ab-35f9-59c2-bb24-fd5953bbaec2","slug":"magnesium-ion","display_name":"Mg2+","entity_type_key":"ion"},"evidence_count":1,"mechanism_event":{"id":"dce0e7fe-db4f-5b9b-9dfb-72590659886f","stable_key":"0f17db03-207f-5910-ac8e-13dfc2f378ce:mg-bckdh-e1-cofactor-occupancy-event","event_type":"biochemical_relationship","label":"The branched-chain ketoacid enzyme contains both vitamin B1-derived cofactor and magnesium.","description":"The human E1b coordinate model 1DTW contains two ThDP molecules and two Mg ions in its alpha2-beta2 assembly.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"187db168-8028-5ce6-9f8b-4bc61ebad1a0","slug":"thiamine-diphosphate","display_name":"Thiamine diphosphate","entity_type_key":"small_molecule"},"role":"bound cofactor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"82b74ccc-3ee5-5622-a8bd-0691de8cdc54","slug":"bckdh-e1","display_name":"Human branched-chain ketoacid dehydrogenase E1","entity_type_key":"protein_complex"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"bff427ab-35f9-59c2-bb24-fd5953bbaec2","slug":"magnesium-ion","display_name":"Mg2+","entity_type_key":"ion"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"Magnesium and thiamine-derived ThDP intersect at mitochondrial carbon metabolism; purified-enzyme responses do not measure whole-body energy supply.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human E1b crystallography, deposited structure 1DTW.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Occupancy supports cofactor architecture; clinical Mg limitation was not tested.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Magnesium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"magnesium","display_name":"Magnesium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The branched-chain ketoacid enzyme contains both vitamin B1-derived cofactor and magnesium.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[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","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"structure_url","value_text":"https://www.ncbi.nlm.nih.gov/Structure/pdb/1DTW","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Recombinant E1b crystal","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"3c3fe31f-b77b-56be-babb-11e29fea7d5a","evidence_kind":"source_excerpt","locator":"Lines 637-648","start_line":637,"end_line":648,"excerpt":"### mg-bckdh-e1-cofactor-occupancy\nThe human E1b coordinate model 1DTW contains two ThDP molecules and two Mg ions in its alpha2-beta2 assembly.\nCondition category: normal\nnutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The branched-chain ketoacid enzyme contains both vitamin B1-derived cofactor and magnesium.\norganism: Homo sapiens\ntissue_or_cell_type: Recombinant E1b crystal\nexperimental_model: Human E1b crystallography, deposited structure 1DTW.\nlimitations: Occupancy supports cofactor architecture; clinical Mg limitation was not tested.\ncross_nutrient: Magnesium and thiamine-derived ThDP intersect at mitochondrial carbon metabolism; purified-enzyme responses do not measure whole-body energy supply.\nstructure_url: https://www.ncbi.nlm.nih.gov/Structure/pdb/1DTW\n[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","model_system":"Human E1b crystallography, deposited structure 1DTW.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study 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","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"dd101e28-1a2e-5a48-9d1e-809c77514866","stable_key":"import-0f17db03-207f-5910-ac8e-13dfc2f378ce","title":"Magnesium: cross-nutrient mechanisms and deficiency (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"e111c412f57143a17e8e65e74e8f7888b5bb9a61099873f4767f527fac19bb07","revision_id":"6b7f04f2-66ed-5859-955f-c2b50d4bf041","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}