{"id":"925574ac-a6ea-57b5-97d7-30eb64662bc2","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-mtrr-nadph-reduction","predicate":"reduces","statement":"NADPH reduction of purified MTRR generated an air-stable flavin semiquinone detected spectroscopically.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"c86c4f7b-b821-56c1-9ef0-3181e55cad31","mechanism_event_label":"NADPH provides electrons to the flavin-containing reductase.","subject":{"id":"4aba2a5e-8d06-5304-bb01-c0402b225a94","slug":"nadph","display_name":"NADPH","entity_type_key":"small_molecule"},"object":{"id":"a0be0dca-5f6e-54a8-b760-e59a0658207d","slug":"mtrr","display_name":"Methionine synthase reductase / MTRR","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"c86c4f7b-b821-56c1-9ef0-3181e55cad31","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-mtrr-nadph-reduction-event","event_type":"biochemical_relationship","label":"NADPH provides electrons to the flavin-containing reductase.","description":"NADPH reduction of purified MTRR generated an air-stable flavin semiquinone detected spectroscopically.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"e2cd7179-f218-54e8-9ce9-7a836ae35fac","slug":"fad","display_name":"FAD","entity_type_key":"small_molecule"},"role":"flavin cofactor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"d3eacf85-1a35-546d-bd30-161474dd9691","slug":"fmn","display_name":"Flavin mononucleotide","entity_type_key":"small_molecule"},"role":"flavin cofactor","stoichiometry":null,"state_label":"","sequence_order":1,"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":2,"notes":""},{"entity":{"id":"a0be0dca-5f6e-54a8-b760-e59a0658207d","slug":"mtrr","display_name":"Methionine synthase reductase / MTRR","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"Nicotinamide-containing NADPH supplies electrons to B2-derived flavins.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution.","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":"Biochemical evidence does not establish a dietary threshold or supplementation benefit.","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":"NADPH provides electrons to the flavin-containing reductase.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. (2001). https://pubmed.ncbi.nlm.nih.gov/11466310/ DOI: 10.1074/jbc.m103707200","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified recombinant enzyme; no intact tissue","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"bbff345b-8b51-54a9-92cf-8526ded2bce0","evidence_kind":"source_excerpt","locator":"Lines 1108-1120","start_line":1108,"end_line":1120,"excerpt":"### b2-mtrr-nadph-reduction\nNADPH reduction of purified MTRR generated an air-stable flavin semiquinone detected spectroscopically.\nCondition category: normal\nnutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: NADPH provides electrons to the flavin-containing reductase.\norganism: Homo sapiens\ntissue_or_cell_type: Purified recombinant enzyme; no intact tissue\nexperimental_model: Recombinant human MTRR purification, flavin analysis, NADPH spectroscopy and methionine-synthase reconstitution.\nlimitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit.\nexposure: Purified-enzyme assay\ncross_nutrient: Nicotinamide-containing NADPH supplies electrons to B2-derived flavins.\nevidence_location: Abstract\n[olteanu2001] Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. 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