{"id":"d8fc2d03-5e88-5652-9f47-deaa6a3599ad","stable_key":"3279ff78-2460-5064-bfc0-3f2987af85a0:melatonin-asmt-sam","predicate":"supplies_methyl_group_to","statement":"Human ASMT has a SAM-dependent O-methyltransferase catalytic domain.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"6cd04e83-ffbb-565c-8a57-4af828cce3c6","mechanism_event_label":"The methyl-donor pool connects this step to methionine and one-carbon metabolism.","subject":{"id":"825f2da2-01bc-5874-a3c6-64f5ac867db5","slug":"s-adenosylmethionine","display_name":"S-Adenosyl-L-methionine","entity_type_key":"small_molecule"},"object":{"id":"b903a716-da57-5b63-bb88-7ac032ece84a","slug":"asmt","display_name":"Human acetylserotonin O-methyltransferase / ASMT","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"6cd04e83-ffbb-565c-8a57-4af828cce3c6","stable_key":"3279ff78-2460-5064-bfc0-3f2987af85a0:melatonin-asmt-sam-event","event_type":"biochemical_relationship","label":"The methyl-donor pool connects this step to methionine and one-carbon metabolism.","description":"Human ASMT has a SAM-dependent O-methyltransferase catalytic domain.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"825f2da2-01bc-5874-a3c6-64f5ac867db5","slug":"s-adenosylmethionine","display_name":"S-Adenosyl-L-methionine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"b903a716-da57-5b63-bb88-7ac032ece84a","slug":"asmt","display_name":"Human acetylserotonin O-methyltransferase / ASMT","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/melatonin-research/22775292.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"6896e0a7e08f764e1ff8c370601b0477c594e4e1c945df52d0f564e9049a9349\", \"start_char\": 0, \"end_char\": 1205, \"text_sha256\": \"6896e0a7e08f764e1ff8c370601b0477c594e4e1c945df52d0f564e9049a9349\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"X-ray structure and radioenzymatic variant characterization","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"SAM-dependent methyltransferase structure and enzyme activity assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Reduced recombinant enzyme activity does not quantify pineal secretion or diagnose a sleep problem in an individual. Variant effects differ; no single universal melatonin-deficiency syndrome.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Melatonin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"melatonin","display_name":"Melatonin","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Human ASMT and 20 nonsynonymous variants","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The methyl-donor pool connects this step to methionine and one-carbon metabolism.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[melatonin-p22775292] Crystal structure and functional mapping of human ASMT, the last enzyme of the melatonin synthesis pathway. (2013). https://pubmed.ncbi.nlm.nih.gov/22775292/ DOI: 10.1111/j.1600-079x.2012.01020.x","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Final melatonin synthesis step","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"565f1ca6-73cb-507b-85f4-7c441b5c84c9","evidence_kind":"source_excerpt","locator":"Lines 214-225","start_line":214,"end_line":225,"excerpt":"### melatonin-asmt-sam\nHuman ASMT has a SAM-dependent O-methyltransferase catalytic domain.\nCondition category: normal\nnutrient_topic: Melatonin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The methyl-donor pool connects this step to methionine and one-carbon metabolism.\norganism: Human ASMT and 20 nonsynonymous variants\ntissue_or_cell_type: Final melatonin synthesis step\nexperimental_model: X-ray structure and radioenzymatic variant characterization\nlimitations: Reduced recombinant enzyme activity does not quantify pineal secretion or diagnose a sleep problem in an individual. Variant effects differ; no single universal melatonin-deficiency syndrome.\nexposure: SAM-dependent methyltransferase structure and enzyme activity assays\nevidence_span: {\"source_cache\": \"artifacts/melatonin-research/22775292.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"6896e0a7e08f764e1ff8c370601b0477c594e4e1c945df52d0f564e9049a9349\", \"start_char\": 0, \"end_char\": 1205, \"text_sha256\": \"6896e0a7e08f764e1ff8c370601b0477c594e4e1c945df52d0f564e9049a9349\"}\n[melatonin-p22775292] Crystal structure and functional mapping of human ASMT, the last enzyme of the melatonin synthesis pathway. (2013). https://pubmed.ncbi.nlm.nih.gov/22775292/ DOI: 10.1111/j.1600-079x.2012.01020.x","model_system":"X-ray structure and radioenzymatic variant characterization","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [melatonin-p22775292] Crystal structure and functional mapping of human ASMT, the last enzyme of the melatonin synthesis pathway. (2013). https://pubmed.ncbi.nlm.nih.gov/22775292/ DOI: 10.1111/j.1600-079x.2012.01020.x","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"bab588de-d217-5038-9c8b-b41222eba08b","stable_key":"import-3279ff78-2460-5064-bfc0-3f2987af85a0","title":"Melatonin: synthesis, receptors, circadian timing 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. 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