{"id":"e605333e-c615-5f77-b542-8dc2868e1892","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-bovine-amidation-ascorbate","predicate":"stimulates","statement":"Bovine intermediate-pituitary granule amidation of D-Tyr-Val-Gly responded to ascorbate, with apparent substrate Km and Vmax changing as the ascorbate concentration changed.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"ac8abcaf-891d-571c-901d-1f8304c74d2d","mechanism_event_label":"Vitamin C helps the pituitary enzyme finish a peptide with an amide group.","subject":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"object":{"id":"a34aa332-22a3-505c-899f-0e8a2b7bc2b3","slug":"bovine-pam","display_name":"Bovine peptidylglycine alpha-amidating monooxygenase","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"ac8abcaf-891d-571c-901d-1f8304c74d2d","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-bovine-amidation-ascorbate-event","event_type":"biochemical_relationship","label":"Vitamin C helps the pituitary enzyme finish a peptide with an amide group.","description":"Bovine intermediate-pituitary granule amidation of D-Tyr-Val-Gly responded to ascorbate, with apparent substrate Km and Vmax changing as the ascorbate concentration changed.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"role":"reducing-cofactor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"a34aa332-22a3-505c-899f-0e8a2b7bc2b3","slug":"bovine-pam","display_name":"Bovine peptidylglycine alpha-amidating monooxygenase","entity_type_key":"protein"},"role":"enzyme-source","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"0df518fc-508b-5187-94c1-22642c4cb772","slug":"d-tyr-val-gly","display_name":"D-Tyr-Val-Gly","entity_type_key":"small_molecule"},"role":"assay-substrate","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"e753d2ce-a8d3-5c8c-bee9-2622eef22206","slug":"d-tyr-val-amide","display_name":"D-Tyr-Val-NH2","entity_type_key":"small_molecule"},"role":"assay-product","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"2a870bb5-05a0-5e51-a70c-a9a843a8b571","slug":"copper-ii","display_name":"Copper(II) ion","entity_type_key":"ion"},"role":"metal-cofactor","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"899c7ab0-6f81-5b38-a6bd-fbb33d66ac8d","slug":"oxygen","display_name":"Molecular oxygen","entity_type_key":"small_molecule"},"role":"cosubstrate","stoichiometry":null,"state_label":"","sequence_order":5,"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":"Bovine intermediate-pituitary secretory-granule kinetic assay","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Synthetic D-Tyr-Val-Gly amidation with varied ascorbate, oxygen and divalent-metal chelators/copper.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"The old granule preparation is not a purified modern PAM-domain assay; synthetic substrate kinetics do not quantify all hormone amidation.","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","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Vitamin C helps the pituitary enzyme finish a peptide with an amide group.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[pam1983] Identification in pituitary tissue of a peptide alpha-amidation activity that acts on glycine-extended peptides and requires molecular oxygen, copper, and ascorbic acid. (1983). https://pubmed.ncbi.nlm.nih.gov/6576381/ DOI: 10.1073/pnas.80.16.5144","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Pituitary secretory granules","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"0e928db6-8d60-57e2-a025-deff0585d1cc","evidence_kind":"source_excerpt","locator":"Lines 859-870","start_line":859,"end_line":870,"excerpt":"### vc-enzyme-bovine-amidation-ascorbate\nBovine intermediate-pituitary granule amidation of D-Tyr-Val-Gly responded to ascorbate, with apparent substrate Km and Vmax changing as the ascorbate concentration changed.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Vitamin C helps the pituitary enzyme finish a peptide with an amide group.\norganism: Bos taurus\ntissue_or_cell_type: Pituitary secretory granules\nexperimental_model: Bovine intermediate-pituitary secretory-granule kinetic assay\nlimitations: The old granule preparation is not a purified modern PAM-domain assay; synthetic substrate kinetics do not quantify all hormone amidation.\ncross_nutrient: Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.\nexposure: Synthetic D-Tyr-Val-Gly amidation with varied ascorbate, oxygen and divalent-metal chelators/copper.\n[pam1983] Identification in pituitary tissue of a peptide alpha-amidation activity that acts on glycine-extended peptides and requires molecular oxygen, copper, and ascorbic acid. (1983). https://pubmed.ncbi.nlm.nih.gov/6576381/ DOI: 10.1073/pnas.80.16.5144","model_system":"Bovine intermediate-pituitary secretory-granule kinetic assay","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [pam1983] Identification in pituitary tissue of a peptide alpha-amidation activity that acts on glycine-extended peptides and requires molecular oxygen, copper, and ascorbic acid. (1983). https://pubmed.ncbi.nlm.nih.gov/6576381/ DOI: 10.1073/pnas.80.16.5144","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"fa811221-13bd-5c10-adc1-eaf097c7703c","stable_key":"import-cb568d28-484a-5c2e-9fcc-2d780358e514","title":"Vitamin C: 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":"b7fd83f956abb81855f2ea23199ba14e465cd91f4a2ac560277ec21ddafd7bfc","revision_id":"6cde9bbb-d712-5746-82a6-85b144253efa","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}