{"id":"5570a502-6ebf-5397-bf2a-0148727e7695","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-kmo-kynurenine-hydroxylation","predicate":"hydroxylates","statement":"Human KMO membrane assays measured kynurenine conversion to 3-hydroxykynurenine with NADPH; at 200 micromolar NADPH, kynurenine Km was 2 micromolar.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"8e4a61d9-7f1b-5806-a26d-139327667bc0","mechanism_event_label":"A flavin enzyme directs tryptophan-derived kynurenine into the hydroxylated branch.","subject":{"id":"5769b5e3-bbb8-5d36-a877-eeb3e3e27b31","slug":"kmo","display_name":"Human kynurenine 3-monooxygenase / KMO","entity_type_key":"protein"},"object":{"id":"ce72cbd6-7077-5f23-a859-a8000a3f8194","slug":"kynurenine","display_name":"L-Kynurenine","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"8e4a61d9-7f1b-5806-a26d-139327667bc0","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-kmo-kynurenine-hydroxylation-event","event_type":"biochemical_relationship","label":"A flavin enzyme directs tryptophan-derived kynurenine into the hydroxylated branch.","description":"Human KMO membrane assays measured kynurenine conversion to 3-hydroxykynurenine with NADPH; at 200 micromolar NADPH, kynurenine Km was 2 micromolar.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"ce72cbd6-7077-5f23-a859-a8000a3f8194","slug":"kynurenine","display_name":"L-Kynurenine","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"215d55a2-1657-589c-aaf4-afd1957859e7","slug":"3-hydroxykynurenine","display_name":"3-Hydroxy-L-kynurenine","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"e2cd7179-f218-54e8-9ce9-7a836ae35fac","slug":"fad","display_name":"FAD","entity_type_key":"small_molecule"},"role":"bound redox cofactor","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"4aba2a5e-8d06-5304-bb01-c0402b225a94","slug":"nadph","display_name":"NADPH","entity_type_key":"small_molecule"},"role":"electron donor","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"5769b5e3-bbb8-5d36-a877-eeb3e3e27b31","slug":"kmo","display_name":"Human kynurenine 3-monooxygenase / KMO","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"B2-FAD and nicotinamide-containing NADPH support a branch upstream of de novo niacin synthesis.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Fig 2f and Methods: kinetic assays; interpret species separately","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human KMO in Sf9 membrane preparations; mass-spectrometry kinetics; separate P. fluorescens KMO crystallography.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Purified-enzyme assay","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Human functional assays and bacterial structures are distinct evidence; this experiment did not test dietary B2 restriction or total NAD synthesis.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Riboflavin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"riboflavin","display_name":"Riboflavin (vitamin B2)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A flavin enzyme directs tryptophan-derived kynurenine into the hydroxylated branch.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[hutchinson2017] Structural and mechanistic basis of differentiated inhibitors of the acute pancreatitis target kynurenine-3-monooxygenase. (2017). https://pubmed.ncbi.nlm.nih.gov/28604669/ DOI: 10.1038/ncomms15827","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Sf9 membrane fraction expressing human KMO","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"96a15e0f-220f-5bf2-9be8-e6df396faebe","evidence_kind":"source_excerpt","locator":"Lines 1234-1246","start_line":1234,"end_line":1246,"excerpt":"### b2-kmo-kynurenine-hydroxylation\nHuman KMO membrane assays measured kynurenine conversion to 3-hydroxykynurenine with NADPH; at 200 micromolar NADPH, kynurenine Km was 2 micromolar.\nCondition category: normal\nnutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A flavin enzyme directs tryptophan-derived kynurenine into the hydroxylated branch.\norganism: Homo sapiens\ntissue_or_cell_type: Sf9 membrane fraction expressing human KMO\nexperimental_model: Human KMO in Sf9 membrane preparations; mass-spectrometry kinetics; separate P. fluorescens KMO crystallography.\nlimitations: Human functional assays and bacterial structures are distinct evidence; this experiment did not test dietary B2 restriction or total NAD synthesis.\nexposure: Purified-enzyme assay\ncross_nutrient: B2-FAD and nicotinamide-containing NADPH support a branch upstream of de novo niacin synthesis.\nevidence_location: Fig 2f and Methods: kinetic assays; interpret species separately\n[hutchinson2017] Structural and mechanistic basis of differentiated inhibitors of the acute pancreatitis target kynurenine-3-monooxygenase. (2017). https://pubmed.ncbi.nlm.nih.gov/28604669/ DOI: 10.1038/ncomms15827","model_system":"Human KMO in Sf9 membrane preparations; mass-spectrometry kinetics; separate P. fluorescens KMO crystallography.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [hutchinson2017] Structural and mechanistic basis of differentiated inhibitors of the acute pancreatitis target kynurenine-3-monooxygenase. (2017). https://pubmed.ncbi.nlm.nih.gov/28604669/ DOI: 10.1038/ncomms15827","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"4f7c9578-82bf-5e2d-b5c4-72a79fb4f6af","stable_key":"import-548ab9d6-3a9b-5bed-879c-17d03813b636","title":"Riboflavin: 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":"680cb6bc8249877f2410f551807f10d390fdd719014137d7414ba3420e29228d","revision_id":"7a61e299-908d-5372-860b-99ed190f9d7a","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}