{"id":"865334cb-d09c-52f9-9fe6-981223d180ea","stable_key":"0f17db03-207f-5910-ac8e-13dfc2f378ce:mg-tkt-other-divalent-cations","predicate":"supports","statement":"Reconstituted erythrocyte transketolase activity ranked Co2+ < Mn2+ < Ca2+ < Mg2+ in the tested assay.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"8a823ea9-a607-5636-a75d-bdd18ad61792","mechanism_event_label":"Several divalent metals supported this B1-dependent enzyme; magnesium worked best here.","subject":{"id":"e359bc15-e675-5d83-b0fe-1d70814e130b","slug":"calcium-ion","display_name":"Calcium ion","entity_type_key":"ion"},"object":{"id":"c95c645c-ae67-5911-871e-4f796a17faec","slug":"tkt","display_name":"Human transketolase","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"8a823ea9-a607-5636-a75d-bdd18ad61792","stable_key":"0f17db03-207f-5910-ac8e-13dfc2f378ce:mg-tkt-other-divalent-cations-event","event_type":"biochemical_relationship","label":"Several divalent metals supported this B1-dependent enzyme; magnesium worked best here.","description":"Reconstituted erythrocyte transketolase activity ranked Co2+ < Mn2+ < Ca2+ < Mg2+ in the tested assay.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"bff427ab-35f9-59c2-bb24-fd5953bbaec2","slug":"magnesium-ion","display_name":"Mg2+","entity_type_key":"ion"},"role":"highest-activity tested metal","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"a8082b11-c484-5792-bb81-48e8e699cbe4","slug":"manganese-ion","display_name":"Mn2+","entity_type_key":"ion"},"role":"replacement metal","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"6409ee5b-28f4-509c-8ad6-4098117cfaec","slug":"cobalt-ion","display_name":"Cobalt(II) ion","entity_type_key":"ion"},"role":"replacement metal","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"187db168-8028-5ce6-9f8b-4bc61ebad1a0","slug":"thiamine-diphosphate","display_name":"Thiamine diphosphate","entity_type_key":"small_molecule"},"role":"cofactor","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"e359bc15-e675-5d83-b0fe-1d70814e130b","slug":"calcium-ion","display_name":"Calcium ion","entity_type_key":"ion"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"c95c645c-ae67-5911-871e-4f796a17faec","slug":"tkt","display_name":"Human transketolase","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"Magnesium availability supports vitamin B1 activation or cofactor use in the specified preparation; this does not establish a dietary threshold or universal treatment failure.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human erythrocyte transketolase; sulfur-35 ThDP binding and divalent-ion reconstitution.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Replacement in vitro does not establish physiological substitution during Mg deficiency.","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":"Several divalent metals supported this B1-dependent enzyme; magnesium worked best here.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[jung-1988-tkt] Studies on the nature of thiamine pyrophosphate binding and dependency on divalent cations of transketolase from human erythrocytes (1988). https://pubmed.ncbi.nlm.nih.gov/3248678/ DOI: 10.1016/0020-711x(88)90228-5","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Erythrocyte enzyme","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"ae623b11-4ff4-5e91-8e0d-faa8d29f61b3","evidence_kind":"source_excerpt","locator":"Lines 565-575","start_line":565,"end_line":575,"excerpt":"### mg-tkt-other-divalent-cations\nReconstituted erythrocyte transketolase activity ranked Co2+ < Mn2+ < Ca2+ < Mg2+ in the tested assay.\nCondition category: normal\nnutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Several divalent metals supported this B1-dependent enzyme; magnesium worked best here.\norganism: Homo sapiens\ntissue_or_cell_type: Erythrocyte enzyme\nexperimental_model: Human erythrocyte transketolase; sulfur-35 ThDP binding and divalent-ion reconstitution.\nlimitations: Replacement in vitro does not establish physiological substitution during Mg deficiency.\ncross_nutrient: Magnesium availability supports vitamin B1 activation or cofactor use in the specified preparation; this does not establish a dietary threshold or universal treatment failure.\n[jung-1988-tkt] Studies on the nature of thiamine pyrophosphate binding and dependency on divalent cations of transketolase from human erythrocytes (1988). https://pubmed.ncbi.nlm.nih.gov/3248678/ DOI: 10.1016/0020-711x(88)90228-5","model_system":"Human erythrocyte transketolase; sulfur-35 ThDP binding and divalent-ion reconstitution.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [jung-1988-tkt] Studies on the nature of thiamine pyrophosphate binding and dependency on divalent cations of transketolase from human erythrocytes (1988). https://pubmed.ncbi.nlm.nih.gov/3248678/ DOI: 10.1016/0020-711x(88)90228-5","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}