{"id":"59906e2c-b4ff-5f4a-9e7e-a616162441a5","stable_key":"1310afbd-6010-586e-805d-551d846da421:b6-neuro-theophylline-pdxk","predicate":"inhibits","statement":"Theophylline inhibited purified human PDXK, with Ki 50 micromolar, and occupied its vitamin-substrate site.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"2383b23b-c84f-5f84-aeea-64ea15bdb6d9","mechanism_event_label":"This drug can interfere with B6 activation in an enzyme assay.","subject":{"id":"544c8ab3-8476-576f-bdae-31cd595a980e","slug":"theophylline","display_name":"Theophylline","entity_type_key":"small_molecule"},"object":{"id":"d2d46db7-13a4-595f-adaa-70ad6ca31a6c","slug":"pdxk","display_name":"Pyridoxal kinase / PDXK","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"2383b23b-c84f-5f84-aeea-64ea15bdb6d9","stable_key":"1310afbd-6010-586e-805d-551d846da421:b6-neuro-theophylline-pdxk-event","event_type":"biochemical_relationship","label":"This drug can interfere with B6 activation in an enzyme assay.","description":"Theophylline inhibited purified human PDXK, with Ki 50 micromolar, and occupied its vitamin-substrate site.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"544c8ab3-8476-576f-bdae-31cd595a980e","slug":"theophylline","display_name":"Theophylline","entity_type_key":"small_molecule"},"role":"inhibitor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"d2d46db7-13a4-595f-adaa-70ad6ca31a6c","slug":"pdxk","display_name":"Pyridoxal kinase / PDXK","entity_type_key":"protein"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"9bf6269d-9e01-553d-bd8b-11a0d613bfca","slug":"pyridoxal","display_name":"Pyridoxal","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"6b656ff5-9532-5da4-8eea-8ca163a48649","slug":"pyridoxal-phosphate","display_name":"PLP","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"experimental_model","value_text":"Purified human PDXK; crystallography and inhibition kinetics","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Purified-enzyme inhibition series; 2.1 angstrom crystal structure.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Other preparations yielded different Ki values; this is assay context, not a nutritional threshold.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b6","display_name":"Vitamin B6","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"This drug can interfere with B6 activation in an enzyme assay.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[gandhi-2012-pdxk-inhibitors] Crystal Structures of Human Pyridoxal Kinase in Complex with the Neurotoxins, Ginkgotoxin and Theophylline: Insights into Pyridoxal Kinase Inhibition (2012). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040954 DOI: 10.1371/journal.pone.0040954","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified recombinant protein; no intact tissue","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"73517f2e-5017-530d-86e7-b90d3ed4f0b6","evidence_kind":"source_excerpt","locator":"Lines 1220-1230","start_line":1220,"end_line":1230,"excerpt":"### b6-neuro-theophylline-pdxk\nTheophylline inhibited purified human PDXK, with Ki 50 micromolar, and occupied its vitamin-substrate site.\nCondition category: machinery_impairment\nnutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: This drug can interfere with B6 activation in an enzyme assay.\norganism: Homo sapiens\ntissue_or_cell_type: Purified recombinant protein; no intact tissue\nexperimental_model: Purified human PDXK; crystallography and inhibition kinetics\nlimitations: Other preparations yielded different Ki values; this is assay context, not a nutritional threshold.\nexposure: Purified-enzyme inhibition series; 2.1 angstrom crystal structure.\n[gandhi-2012-pdxk-inhibitors] Crystal Structures of Human Pyridoxal Kinase in Complex with the Neurotoxins, Ginkgotoxin and Theophylline: Insights into Pyridoxal Kinase Inhibition (2012). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040954 DOI: 10.1371/journal.pone.0040954","model_system":"Purified human PDXK; crystallography and inhibition kinetics","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [gandhi-2012-pdxk-inhibitors] Crystal Structures of Human Pyridoxal Kinase in Complex with the Neurotoxins, Ginkgotoxin and Theophylline: Insights into Pyridoxal Kinase Inhibition (2012). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040954 DOI: 10.1371/journal.pone.0040954","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"251773bb-16f5-5903-b135-db4a61d9dec4","stable_key":"import-1310afbd-6010-586e-805d-551d846da421","title":"Vitamin B6: 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":"ef0019b344b2219220f801a84d0d138ff6880c1be1a59540d9034bfa4334f61e","revision_id":"cac3555f-48af-5c52-a84e-add4482c87fb","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}