{"id":"0038b3aa-4f89-55a9-a960-066a481e9470","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-mthfr-methylfolate-production","predicate":"catalyzes","statement":"HPLC assays measured human MTHFR reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate using NADPH.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"25ca06aa-54b4-5a9b-bd2d-736ee94e21e8","mechanism_event_label":"The enzyme makes the methylfolate used in homocysteine recycling.","subject":{"id":"9fc32b1a-0f08-544c-a361-1c728203b6ec","slug":"mthfr","display_name":"Methylenetetrahydrofolate reductase / MTHFR","entity_type_key":"protein"},"object":{"id":"23f48782-478e-5f62-874a-31273c075fe7","slug":"5-methyltetrahydrofolate","display_name":"5-Methyltetrahydrofolate","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"25ca06aa-54b4-5a9b-bd2d-736ee94e21e8","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-mthfr-methylfolate-production-event","event_type":"biochemical_relationship","label":"The enzyme makes the methylfolate used in homocysteine recycling.","description":"HPLC assays measured human MTHFR reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate using NADPH.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"0413b195-325e-5757-a72b-f445d65c17bc","slug":"5-10-methylenetetrahydrofolate","display_name":"5,10-Methylenetetrahydrofolate","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"23f48782-478e-5f62-874a-31273c075fe7","slug":"5-methyltetrahydrofolate","display_name":"5-Methyltetrahydrofolate","entity_type_key":"small_molecule"},"role":"product","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":"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":3,"notes":""},{"entity":{"id":"9fc32b1a-0f08-544c-a361-1c728203b6ec","slug":"mthfr","display_name":"Methylenetetrahydrofolate reductase / MTHFR","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"B2-FAD, folate and nicotinamide-containing NADPH participate in one reaction.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Results: kinetics, FAD occupancy and SAM inhibition; Table 1; Figs 2-4, 6","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant human MTHFR expressed in Sf9 cells; mass spectrometry, 2.5-A structure, HPLC activity assays.","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":"The enzyme makes the methylfolate used in homocysteine recycling.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[froese2018] Structural basis for the regulation of human 5,10-methylenetetrahydrofolate reductase by phosphorylation and S-adenosylmethionine inhibition. (2018). https://pubmed.ncbi.nlm.nih.gov/29891918/ DOI: 10.1038/s41467-018-04735-2","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":"d1e348fa-10cf-568f-9afb-636226a1cdbe","evidence_kind":"source_excerpt","locator":"Lines 1010-1022","start_line":1010,"end_line":1022,"excerpt":"### b2-mthfr-methylfolate-production\nHPLC assays measured human MTHFR reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate using NADPH.\nCondition category: normal\nnutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The enzyme makes the methylfolate used in homocysteine recycling.\norganism: Homo sapiens\ntissue_or_cell_type: Purified recombinant enzyme; no intact tissue\nexperimental_model: Recombinant human MTHFR expressed in Sf9 cells; mass spectrometry, 2.5-A structure, HPLC activity assays.\nlimitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit.\nexposure: Purified-enzyme assay\ncross_nutrient: B2-FAD, folate and nicotinamide-containing NADPH participate in one reaction.\nevidence_location: Results: kinetics, FAD occupancy and SAM inhibition; Table 1; Figs 2-4, 6\n[froese2018] Structural basis for the regulation of human 5,10-methylenetetrahydrofolate reductase by phosphorylation and S-adenosylmethionine inhibition. (2018). https://pubmed.ncbi.nlm.nih.gov/29891918/ DOI: 10.1038/s41467-018-04735-2","model_system":"Recombinant human MTHFR expressed in Sf9 cells; mass spectrometry, 2.5-A structure, HPLC activity assays.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [froese2018] Structural basis for the regulation of human 5,10-methylenetetrahydrofolate reductase by phosphorylation and S-adenosylmethionine inhibition. 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