{"id":"9b6fd26b-7963-53a7-9cd0-d2a3d66bea5e","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-pam-oxidative-inactivation","predicate":"inactivates-in-assay","statement":"In time- and concentration-dependent purified-protein experiments, ascorbate inactivated the full amidation activity of recombinant rat 75-kDa PAM measured with dansyl-Tyr-Val-Gly.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"9f9d2c76-e2f6-556f-b183-277b8150a5cd","mechanism_event_label":"The same vitamin that supports the enzyme can damage its hydroxylating activity under particular cell-free redox conditions.","subject":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"object":{"id":"cb1d701b-c3cb-5f8e-9bbe-c796d6028a0e","slug":"rat-pam-type-a-75kda","display_name":"Recombinant rat type-A 75-kDa peptidylglycine amidating enzyme","entity_type_key":"protein_state"},"evidence_count":1,"mechanism_event":{"id":"9f9d2c76-e2f6-556f-b183-277b8150a5cd","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-pam-oxidative-inactivation-event","event_type":"biochemical_relationship","label":"The same vitamin that supports the enzyme can damage its hydroxylating activity under particular cell-free redox conditions.","description":"In time- and concentration-dependent purified-protein experiments, ascorbate inactivated the full amidation activity of recombinant rat 75-kDa PAM measured with dansyl-Tyr-Val-Gly.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"role":"assay-exposure","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"cb1d701b-c3cb-5f8e-9bbe-c796d6028a0e","slug":"rat-pam-type-a-75kda","display_name":"Recombinant rat type-A 75-kDa peptidylglycine amidating enzyme","entity_type_key":"protein_state"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"ebf9ae06-3ee9-5853-b372-0c7d51012209","slug":"dansyl-tyr-val-gly","display_name":"Dansyl-Tyr-Val-Gly","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"62a1bc7d-0223-5579-8771-bceb91d3a9c3","slug":"dansyl-tyr-val-amide","display_name":"Dansyl-Tyr-Val-NH2","entity_type_key":"small_molecule"},"role":"product-readout","stoichiometry":null,"state_label":"","sequence_order":3,"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":"Recombinant rat type-A 75-kDa PAM, purified enzyme assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Time/concentration series of ascorbate, DHA or H2O2; fluorescent peptide substrate or pre-hydroxylated intermediate.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Assay redox damage, not evidence that dietary vitamin C suppresses hormone amidation in vivo; accessible abstract does not specify full concentration range.","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":"Rattus norvegicus (protein)","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The same vitamin that supports the enzyme can damage its hydroxylating activity under particular cell-free redox conditions.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[pam1992] Selective inactivation of the hydroxylase activity of bifunctional rat peptidylglycine alpha-amidating enzyme. (1992). https://pubmed.ncbi.nlm.nih.gov/1567215/ DOI: 10.1016/0003-9861(92)90730-k","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cell-free recombinant rat protein","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"28c557b2-6933-57ed-959c-5338d3368f7d","evidence_kind":"source_excerpt","locator":"Lines 911-922","start_line":911,"end_line":922,"excerpt":"### vc-enzyme-pam-oxidative-inactivation\nIn time- and concentration-dependent purified-protein experiments, ascorbate inactivated the full amidation activity of recombinant rat 75-kDa PAM measured with dansyl-Tyr-Val-Gly.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The same vitamin that supports the enzyme can damage its hydroxylating activity under particular cell-free redox conditions.\norganism: Rattus norvegicus (protein)\ntissue_or_cell_type: Cell-free recombinant rat protein\nexperimental_model: Recombinant rat type-A 75-kDa PAM, purified enzyme assays\nlimitations: Assay redox damage, not evidence that dietary vitamin C suppresses hormone amidation in vivo; accessible abstract does not specify full concentration range.\ncross_nutrient: Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.\nexposure: Time/concentration series of ascorbate, DHA or H2O2; fluorescent peptide substrate or pre-hydroxylated intermediate.\n[pam1992] Selective inactivation of the hydroxylase activity of bifunctional rat peptidylglycine alpha-amidating enzyme. (1992). https://pubmed.ncbi.nlm.nih.gov/1567215/ DOI: 10.1016/0003-9861(92)90730-k","model_system":"Recombinant rat type-A 75-kDa PAM, purified enzyme assays","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [pam1992] Selective inactivation of the hydroxylase activity of bifunctional rat peptidylglycine alpha-amidating enzyme. (1992). https://pubmed.ncbi.nlm.nih.gov/1567215/ DOI: 10.1016/0003-9861(92)90730-k","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. 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