{"id":"8fb86177-8532-5789-9362-98bad87562ca","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-cons-nnmt-sam-standard","predicate":"has_limited_effect","statement":"At standard 100 micromolar medium methionine, NNMT overexpression changed SAM by less than 1.5-fold despite increased SAH.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"neutral","is_public":true,"mechanism_event_id":"dae03084-39a3-5434-a53b-39c023fa71b8","mechanism_event_label":"A higher methyl-transfer product did not necessarily mean a large fall in SAM.","subject":{"id":"68273ca3-19da-57e0-85bb-2f1245928df5","slug":"nnmt","display_name":"Human NNMT","entity_type_key":"protein"},"object":{"id":"7e7b818f-78ef-5a36-83d4-73d46ad20054","slug":"cellular-sam-concentration","display_name":"Cellular S-adenosylmethionine concentration","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"dae03084-39a3-5434-a53b-39c023fa71b8","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-cons-nnmt-sam-standard-event","event_type":"biochemical_relationship","label":"A higher methyl-transfer product did not necessarily mean a large fall in SAM.","description":"At standard 100 micromolar medium methionine, NNMT overexpression changed SAM by less than 1.5-fold despite increased SAH.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"68273ca3-19da-57e0-85bb-2f1245928df5","slug":"nnmt","display_name":"Human NNMT","entity_type_key":"protein"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"9d39f561-740b-5f67-bba7-8a72ef612a99","slug":"methionine","display_name":"L-Methionine","entity_type_key":"small_molecule"},"role":"culture_nutrient","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"825f2da2-01bc-5874-a3c6-64f5ac867db5","slug":"s-adenosylmethionine","display_name":"S-Adenosyl-L-methionine","entity_type_key":"small_molecule"},"role":"methyl_donor","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"7e7b818f-78ef-5a36-83d4-73d46ad20054","slug":"cellular-sam-concentration","display_name":"Cellular S-adenosylmethionine concentration","entity_type_key":"cellular_process"},"role":"outcome","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"e84829b1-0607-558e-8add-aaa3af4747e7","slug":"s-adenosylhomocysteine","display_name":"S-Adenosyl-L-homocysteine","entity_type_key":"small_molecule"},"role":"coproduct","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/niacin-consumption-sources/nnmt2013.txt\", \"locator\": \"Full text, normalized paragraph 24\", \"start_char\": 12788, \"end_char\": 14928, \"file_sha256\": \"7d88fd656ba772962185234a9bd021e40a9b83f9156db836f723eba06b68acca\", \"text_sha256\": \"760641ee47babbc4c1261afe881ea4baa14ae9032d0538bd467c9957224059f7\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Targeted LC-MS metabolomics","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"100 micromolar methionine culture medium; NNMT overexpression","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Engineered human cancer-cell culture, not healthy-human niacin repletion. SAM consumption does not establish systemic methyl depletion or a need for folate/B12 supplements.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Niacin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"niacin","display_name":"Niacin (vitamin B3)","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Human","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A higher methyl-transfer product did not necessarily mean a large fall in SAM.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[b3-cons-nnmt2013] NNMT promotes epigenetic remodeling in cancer by creating a metabolic methylation sink. (2013). https://pubmed.ncbi.nlm.nih.gov/23455543/ DOI: 10.1038/nchembio.1204","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Human cancer-cell overexpression models","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"4c0175ac-4541-5999-b7c7-2f194b6bde1b","evidence_kind":"source_excerpt","locator":"Lines 775-787","start_line":775,"end_line":787,"excerpt":"### b3-cons-nnmt-sam-standard\nAt standard 100 micromolar medium methionine, NNMT overexpression changed SAM by less than 1.5-fold despite increased SAH.\nCondition category: normal\nnutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A higher methyl-transfer product did not necessarily mean a large fall in SAM.\norganism: Human\ntissue_or_cell_type: Human cancer-cell overexpression models\nexperimental_model: Targeted LC-MS metabolomics\nlimitations: Engineered human cancer-cell culture, not healthy-human niacin repletion. SAM consumption does not establish systemic methyl depletion or a need for folate/B12 supplements.\nexposure: 100 micromolar methionine culture medium; NNMT overexpression\ncross_nutrient: true\nevidence_span: {\"source_cache\": \"artifacts/niacin-consumption-sources/nnmt2013.txt\", \"locator\": \"Full text, normalized paragraph 24\", \"start_char\": 12788, \"end_char\": 14928, \"file_sha256\": \"7d88fd656ba772962185234a9bd021e40a9b83f9156db836f723eba06b68acca\", \"text_sha256\": \"760641ee47babbc4c1261afe881ea4baa14ae9032d0538bd467c9957224059f7\"}\n[b3-cons-nnmt2013] NNMT promotes epigenetic remodeling in cancer by creating a metabolic methylation sink. (2013). https://pubmed.ncbi.nlm.nih.gov/23455543/ DOI: 10.1038/nchembio.1204","model_system":"Targeted LC-MS metabolomics","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [b3-cons-nnmt2013] NNMT promotes epigenetic remodeling in cancer by creating a metabolic methylation sink. (2013). https://pubmed.ncbi.nlm.nih.gov/23455543/ DOI: 10.1038/nchembio.1204","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"a62b7b5b-786a-57e9-85e9-67c6912a5054","stable_key":"import-a9dd23c6-978a-5755-8bd8-f29bd1fe0cda","title":"Niacin: NAD metabolism, 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":"a8cac59639322f74812ce12eef338c2f6c385c04cc4af6ab511fc7c972f0c2e6","revision_id":"bec8fc45-12e7-5f75-a814-5d72ed015d01","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}