{"id":"9f5e3275-eeeb-5cda-8bf4-47cccf1cb24f","stable_key":"41a89233-da9a-5b7b-9c18-e19bbadcfe2d:methionine-ahcy-reaction","predicate":"hydrolyzes","statement":"AHCY catalyzes reversible conversion between SAH and adenosine plus homocysteine; product clearance favors net SAH removal.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"d8b76fe8-ba1a-5299-afb3-e522fb242b48","mechanism_event_label":"After methyl transfer, the spent donor must be processed.","subject":{"id":"1a5e2abf-e98c-5ee2-8197-4434fcc1e88a","slug":"ahcy","display_name":"Human adenosylhomocysteinase / AHCY","entity_type_key":"protein"},"object":{"id":"e84829b1-0607-558e-8add-aaa3af4747e7","slug":"s-adenosylhomocysteine","display_name":"S-Adenosyl-L-homocysteine","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"d8b76fe8-ba1a-5299-afb3-e522fb242b48","stable_key":"41a89233-da9a-5b7b-9c18-e19bbadcfe2d:methionine-ahcy-reaction-event","event_type":"observed_relationship","label":"After methyl transfer, the spent donor must be processed.","description":"AHCY catalyzes reversible conversion between SAH and adenosine plus homocysteine; product clearance favors net SAH removal.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"1a5e2abf-e98c-5ee2-8197-4434fcc1e88a","slug":"ahcy","display_name":"Human adenosylhomocysteinase / AHCY","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"e84829b1-0607-558e-8add-aaa3af4747e7","slug":"s-adenosylhomocysteine","display_name":"S-Adenosyl-L-homocysteine","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"9d39f561-740b-5f67-bba7-8a72ef612a99","slug":"methionine","display_name":"L-Methionine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"b1001072-f1ab-54a1-80fd-d15a41e31adb","slug":"adenosine","display_name":"Adenosine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"5b635b42-bc0d-5c54-aa94-9cf76cd0ed47","slug":"homocysteine","display_name":"Homocysteine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Established reaction in the human AHCY-deficiency investigation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Reaction equilibrium and cellular product removal matter; plasma concentrations do not uniquely define tissue flux.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Methionine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"methionine","display_name":"L-Methionine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"After methyl transfer, the spent donor must be processed.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"S-adenosylhomocysteine hydrolase deficiency in a human: a genetic disorder of methionine metabolism. · 2004 · https://pubmed.ncbi.nlm.nih.gov/15024124/ · DOI 10.1073/pnas.0400658101","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"bc39fbc8-9219-5a21-bff6-0ca15f00f3c5","evidence_kind":"source_excerpt","locator":"Lines 172-178","start_line":172,"end_line":178,"excerpt":"## methionine-ahcy-reaction\nAfter methyl transfer, the spent donor must be processed.\nAHCY catalyzes reversible conversion between SAH and adenosine plus homocysteine; product clearance favors net SAH removal.\nModel: Established reaction in the human AHCY-deficiency investigation.\nLimitations: Reaction equilibrium and cellular product removal matter; plasma concentrations do not uniquely define tissue flux.\nEvidence access: Primary abstract\nS-adenosylhomocysteine hydrolase deficiency in a human: a genetic disorder of methionine metabolism. · 2004 · https://pubmed.ncbi.nlm.nih.gov/15024124/ · DOI 10.1073/pnas.0400658101","model_system":"Established reaction in the human AHCY-deficiency investigation.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"d969b004-ccc2-5bb4-9109-8ac649137ad1","stable_key":"import-41a89233-da9a-5b7b-9c18-e19bbadcfe2d","title":"L-Methionine: transport, methylation, sulfur metabolism and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text.","file_path":"","sha256":"f1c706ef72932eed85df234b6c3304158d503d626a63c69b02a453c162700d26","revision_id":"549035e0-3a72-550a-8a55-e8c5baa51b0d","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}