{"id":"2e4fab31-16f7-5dfc-8c84-defdfabb41b6","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:c-reg-phd-ascorbate-not-stoichiometric","predicate":"does-not-cause-substrate-coupled-consumption","statement":"HPLC showed only a small decline in ascorbate during the PHD2 peptide reaction, independent of hydroxyl-acceptor substrate, providing no evidence that coupled prolyl hydroxylation consumed ascorbate stoichiometrically.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"neutral","is_public":true,"mechanism_event_id":"85d36e4f-247e-5959-9acb-d7b9acf28d51","mechanism_event_label":"Vitamin C was not used up once for every hydroxylation event in this enzyme assay.","subject":{"id":"8681acd7-4f56-59e0-a757-37b8376c8bde","slug":"egln1","display_name":"EGLN1 / PHD2","entity_type_key":"protein"},"object":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"85d36e4f-247e-5959-9acb-d7b9acf28d51","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:c-reg-phd-ascorbate-not-stoichiometric-event","event_type":"biochemical_relationship","label":"Vitamin C was not used up once for every hydroxylation event in this enzyme assay.","description":"HPLC showed only a small decline in ascorbate during the PHD2 peptide reaction, independent of hydroxyl-acceptor substrate, providing no evidence that coupled prolyl hydroxylation consumed ascorbate stoichiometrically.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"da1a7137-08f2-5a36-8bb6-377fbd32e327","slug":"vitamin-c","display_name":"Vitamin C","entity_type_key":"chemical_species"},"role":"nutrient context","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"59d6d1cd-df32-5b58-b950-3188bc7b95d6","slug":"iron-ii","display_name":"Ferrous iron","entity_type_key":"ion"},"role":"metal cofactor","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"628ddc2d-e4d9-59c7-ae76-0c0cab80a6b1","slug":"2-oxoglutarate","display_name":"2-Oxoglutarate","entity_type_key":"small_molecule"},"role":"cosubstrate","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"8681acd7-4f56-59e0-a757-37b8376c8bde","slug":"egln1","display_name":"EGLN1 / PHD2","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Figure 2C","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant human PHD enzymes; HIF-1 alpha 556–574 peptide hydroxylation detected by VHL/elongin B/C binding; HPLC of reaction ascorbate","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"10 µM FeSO4, 0.5 mM 2-oxoglutarate, pH 7.5, room temperature, 1 h; ascorbate omission/titration and GSH titration; standard ascorbate 2 mM. Ascorbate measured before and after 1 h.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Minor air oxidation remained possible; result does not exclude ascorbate consumption during uncoupled or oxidative-damage reactions.","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":"Homo sapiens protein","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Vitamin C was not used up once for every hydroxylation event in this enzyme assay.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[c-reg-nytko] Vitamin C is dispensable for oxygen sensing in vivo. (2011). https://pubmed.ncbi.nlm.nih.gov/21346252/ DOI: 10.1182/blood-2010-09-307637","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cell-free","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"ed31796f-74ed-5daf-903c-a78adbf007c3","evidence_kind":"source_excerpt","locator":"Lines 1159-1171","start_line":1159,"end_line":1171,"excerpt":"### c-reg-phd-ascorbate-not-stoichiometric\nHPLC showed only a small decline in ascorbate during the PHD2 peptide reaction, independent of hydroxyl-acceptor substrate, providing no evidence that coupled prolyl hydroxylation consumed ascorbate stoichiometrically.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Vitamin C was not used up once for every hydroxylation event in this enzyme assay.\norganism: Homo sapiens protein\ntissue_or_cell_type: Cell-free\nexperimental_model: Recombinant human PHD enzymes; HIF-1 alpha 556–574 peptide hydroxylation detected by VHL/elongin B/C binding; HPLC of reaction ascorbate\nlimitations: Minor air oxidation remained possible; result does not exclude ascorbate consumption during uncoupled or oxidative-damage reactions.\nexposure: 10 µM FeSO4, 0.5 mM 2-oxoglutarate, pH 7.5, room temperature, 1 h; ascorbate omission/titration and GSH titration; standard ascorbate 2 mM. Ascorbate measured before and after 1 h.\ncross_nutrient: true\nevidence_location: Figure 2C\n[c-reg-nytko] Vitamin C is dispensable for oxygen sensing in vivo. (2011). https://pubmed.ncbi.nlm.nih.gov/21346252/ DOI: 10.1182/blood-2010-09-307637","model_system":"Recombinant human PHD enzymes; HIF-1 alpha 556–574 peptide hydroxylation detected by VHL/elongin B/C binding; HPLC of reaction ascorbate","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [c-reg-nytko] Vitamin C is dispensable for oxygen sensing in vivo. (2011). https://pubmed.ncbi.nlm.nih.gov/21346252/ DOI: 10.1182/blood-2010-09-307637","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}