{"id":"094688d7-93e5-57d8-953b-c97eb6e27048","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-mmachc-decyanation","predicate":"reductively-decyanates","statement":"Human MMACHC converted bound cyanocobalamin to cob(II)alamin during NADPH-supported reductive decyanation; EPR identified the product in a base-off coordination state.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"a2a4010e-b877-5ade-b203-7c64dc850509","mechanism_event_label":"Processing removes the cyano group and leaves a reduced B12 intermediate.","subject":{"id":"70ae4c83-37b2-5bd7-931d-021cace41eef","slug":"mmachc","display_name":"Human MMACHC / cobalamin-processing protein CblC","entity_type_key":"protein"},"object":{"id":"4cb4dfbc-6cd9-5bd5-98dc-d0a8fb6cfee4","slug":"cyanocobalamin","display_name":"Cyanocobalamin","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"a2a4010e-b877-5ade-b203-7c64dc850509","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-mmachc-decyanation-event","event_type":"biochemical_relationship","label":"Processing removes the cyano group and leaves a reduced B12 intermediate.","description":"Human MMACHC converted bound cyanocobalamin to cob(II)alamin during NADPH-supported reductive decyanation; 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Materials and Methods: Decyanation of CNCbl","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified human MMACHC with human flavoprotein donor","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Anaerobic CNCbl/MMACHC, NADPH and MTRR or NDOR1","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Processing removes the cyano group and leaves a reduced B12 intermediate.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cell-free assay","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"8d3abed0-6530-5305-854f-fa82f3a356d6","evidence_kind":"source_excerpt","locator":"Lines 669-681","start_line":669,"end_line":681,"excerpt":"### b12-mmachc-decyanation\nHuman MMACHC converted bound cyanocobalamin to cob(II)alamin during NADPH-supported reductive decyanation; EPR identified the product in a base-off coordination state.\nCondition category: normal\nnutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Processing removes the cyano group and leaves a reduced B12 intermediate.\norganism: Homo sapiens\ntissue_or_cell_type: Cell-free assay\nexperimental_model: Purified human MMACHC with human flavoprotein donor\nlimitations: Reconstituted biochemical system; establishes reaction capability rather than the quantitatively dominant pathway in living humans.\nexposure: Anaerobic CNCbl/MMACHC, NADPH and MTRR or NDOR1\ncross_nutrient: true\nevidence_location: Results: Figure 4; Materials and Methods: Decyanation of CNCbl\n[kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105","model_system":"Purified human MMACHC with human flavoprotein donor","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [kim-2008-decyanation] Decyanation of vitamin B12 by a trafficking chaperone (2008). https://pubmed.ncbi.nlm.nih.gov/18779575/ DOI: 10.1073/pnas.0805989105","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"73145023-2982-5848-aff2-8d8875d6b9c5","stable_key":"import-7fc92b9e-9cbf-556e-8719-6b5244625250","title":"Vitamin B12: mechanisms, deficiency and nutrient interactions (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":"ad5b3a51d36e856aa7fdfd1cc23f690b094689bad87d28e1a621a54675a01c92","revision_id":"118bd616-0c13-549f-bfeb-bc439715b89c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}