{"id":"83d4d0cd-8418-5d6d-9ec8-b69d8aa7c5fb","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-dbh-radical-product","predicate":"oxidized-during-dbh-catalysis-to","statement":"Coupling bovine DBH tyramine hydroxylation to semidehydroascorbate reductase identified semidehydroascorbate as the immediate enzymic oxidation product of ascorbate.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"neutral","is_public":true,"mechanism_event_id":"260c63d1-eb0d-5d50-a459-f34c1c87b545","mechanism_event_label":"This copper enzyme takes single electrons from vitamin C, leaving an ascorbyl radical that can be recycled.","subject":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"object":{"id":"17a4b1a5-451a-563f-8f20-2de8f4b0af8e","slug":"ascorbyl-radical","display_name":"Ascorbyl radical","entity_type_key":"chemical_species"},"evidence_count":1,"mechanism_event":{"id":"260c63d1-eb0d-5d50-a459-f34c1c87b545","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-dbh-radical-product-event","event_type":"biochemical_relationship","label":"This copper enzyme takes single electrons from vitamin C, leaving an ascorbyl radical that can be recycled.","description":"Coupling bovine DBH tyramine hydroxylation to semidehydroascorbate reductase identified semidehydroascorbate as the immediate enzymic oxidation product of ascorbate.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"role":"electron-donor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"78df2518-5479-5765-98cd-56c63f91d2a4","slug":"bovine-dbh","display_name":"Bovine dopamine beta-hydroxylase","entity_type_key":"protein"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"db95e69b-dd32-5fd7-8615-62899f42c17e","slug":"tyramine","display_name":"Tyramine","entity_type_key":"small_molecule"},"role":"assay-substrate","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"17a4b1a5-451a-563f-8f20-2de8f4b0af8e","slug":"ascorbyl-radical","display_name":"Ascorbyl radical","entity_type_key":"chemical_species"},"role":"immediate-product","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"e6658c2b-ccff-5122-80a5-2e153f12ba90","slug":"dehydroascorbic-acid","display_name":"Dehydroascorbic acid","entity_type_key":"small_molecule"},"role":"distinguished-oxidation-product","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified bovine DBH coupled to rat-liver or Neurospora semidehydroascorbate reductase","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Tyramine beta-hydroxylation with ascorbate; coupled pyridine-nucleotide oxidation and radical recycling assays.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Heterologous reductase-coupled assay; radical dismutation can subsequently produce DHA, so immediate product and net redox balance must be distinguished.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin C research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-c","display_name":"Vitamin C","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Bos taurus; Rattus norvegicus; Neurospora crassa","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"This copper enzyme takes single electrons from vitamin C, leaving an ascorbyl radical that can be recycled.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[dbh1981] Mechanism of dopamine-beta-hydroxylation. Semidehydroascorbate as the enzyme oxidation product of ascorbate. (1981). https://pubmed.ncbi.nlm.nih.gov/6451628/ DOI: 10.1016/S0021-9258(19)69620-1","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Bovine adrenal-medullary enzyme plus heterologous reductase preparations","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"c498b538-d6f6-59b0-ae93-80f475354a3c","evidence_kind":"source_excerpt","locator":"Lines 807-818","start_line":807,"end_line":818,"excerpt":"### vc-enzyme-dbh-radical-product\nCoupling bovine DBH tyramine hydroxylation to semidehydroascorbate reductase identified semidehydroascorbate as the immediate enzymic oxidation product of ascorbate.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: This copper enzyme takes single electrons from vitamin C, leaving an ascorbyl radical that can be recycled.\norganism: Bos taurus; Rattus norvegicus; Neurospora crassa\ntissue_or_cell_type: Bovine adrenal-medullary enzyme plus heterologous reductase preparations\nexperimental_model: Purified bovine DBH coupled to rat-liver or Neurospora semidehydroascorbate reductase\nlimitations: Heterologous reductase-coupled assay; radical dismutation can subsequently produce DHA, so immediate product and net redox balance must be distinguished.\ncross_nutrient: Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.\nexposure: Tyramine beta-hydroxylation with ascorbate; coupled pyridine-nucleotide oxidation and radical recycling assays.\n[dbh1981] Mechanism of dopamine-beta-hydroxylation. 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