{"id":"87b8264c-58e4-5f6c-b0e9-714534338beb","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-pal-intermediate-cleavage","predicate":"converts","statement":"Purified bovine pituitary PAL catalyzed amidation of N-acetyl-Tyr-Val-alpha-hydroxyglycine, with reported Km 38 micromolar and turnover 220/s for this synthetic intermediate.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"51f76a8c-3a24-5b91-be78-837d70073eb0","mechanism_event_label":"After hydroxylation, a second enzyme domain releases the finished peptide amide.","subject":{"id":"85ec62fd-8771-55c8-8b07-5c2083070879","slug":"bovine-pal-domain","display_name":"Bovine PAM peptidyl-alpha-hydroxyglycine alpha-amidating lyase domain","entity_type_key":"protein_state"},"object":{"id":"2e9844f9-b8bd-5a50-b1c6-5b9c75a91b9d","slug":"acetyl-tyr-val-hydroxyglycine","display_name":"N-acetyl-Tyr-Val-alpha-hydroxyglycine","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"51f76a8c-3a24-5b91-be78-837d70073eb0","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-pal-intermediate-cleavage-event","event_type":"biochemical_relationship","label":"After hydroxylation, a second enzyme domain releases the finished peptide amide.","description":"Purified bovine pituitary PAL catalyzed amidation of N-acetyl-Tyr-Val-alpha-hydroxyglycine, with reported Km 38 micromolar and turnover 220/s for this synthetic intermediate.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"85ec62fd-8771-55c8-8b07-5c2083070879","slug":"bovine-pal-domain","display_name":"Bovine PAM peptidyl-alpha-hydroxyglycine alpha-amidating lyase domain","entity_type_key":"protein_state"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"2e9844f9-b8bd-5a50-b1c6-5b9c75a91b9d","slug":"acetyl-tyr-val-hydroxyglycine","display_name":"N-acetyl-Tyr-Val-alpha-hydroxyglycine","entity_type_key":"small_molecule"},"role":"synthetic-substrate","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"fada964c-3d34-59b2-8f5a-7f4f13b720bc","slug":"acetyl-tyr-val-amide","display_name":"N-acetyl-Tyr-Val-NH2","entity_type_key":"small_molecule"},"role":"synthetic-product","stoichiometry":null,"state_label":"","sequence_order":2,"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 pituitary PAL and bovine-domain expression constructs in HEK293 cells","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Purified PAL with N-acetyl-Tyr-Val-alpha-hydroxyglycine; PHM or PAL-containing constructs expressed in HEK293.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Kinetics belong to this substrate and preparation. PAL is not another ascorbate-consuming hydroxylase; metal inhibition/reactivation in this paper does not establish physiological metal occupancy.","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 (protein); Homo sapiens (expression host)","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"After hydroxylation, a second enzyme domain releases the finished peptide amide.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[pal1991] Peptidyl-alpha-hydroxyglycine alpha-amidating lyase. Purification, characterization, and expression. (1991). https://pubmed.ncbi.nlm.nih.gov/1902227/ DOI: 10.1016/s0021-9258(20)89524-6","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Bovine neurointermediate pituitary; heterologous HEK293","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"22056279-3c18-5d5c-a691-43235c1c1dc5","evidence_kind":"source_excerpt","locator":"Lines 898-909","start_line":898,"end_line":909,"excerpt":"### vc-enzyme-pal-intermediate-cleavage\nPurified bovine pituitary PAL catalyzed amidation of N-acetyl-Tyr-Val-alpha-hydroxyglycine, with reported Km 38 micromolar and turnover 220/s for this synthetic intermediate.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: After hydroxylation, a second enzyme domain releases the finished peptide amide.\norganism: Bos taurus (protein); Homo sapiens (expression host)\ntissue_or_cell_type: Bovine neurointermediate pituitary; heterologous HEK293\nexperimental_model: Purified bovine pituitary PAL and bovine-domain expression constructs in HEK293 cells\nlimitations: Kinetics belong to this substrate and preparation. PAL is not another ascorbate-consuming hydroxylase; metal inhibition/reactivation in this paper does not establish physiological metal occupancy.\ncross_nutrient: Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.\nexposure: Purified PAL with N-acetyl-Tyr-Val-alpha-hydroxyglycine; PHM or PAL-containing constructs expressed in HEK293.\n[pal1991] Peptidyl-alpha-hydroxyglycine alpha-amidating lyase. Purification, characterization, and expression. (1991). https://pubmed.ncbi.nlm.nih.gov/1902227/ DOI: 10.1016/s0021-9258(20)89524-6","model_system":"Purified bovine pituitary PAL and bovine-domain expression constructs in HEK293 cells","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [pal1991] Peptidyl-alpha-hydroxyglycine alpha-amidating lyase. Purification, characterization, and expression. (1991). https://pubmed.ncbi.nlm.nih.gov/1902227/ DOI: 10.1016/s0021-9258(20)89524-6","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}