{"id":"ba83dfb3-7173-5d92-a24d-bcb50e800b83","stable_key":"1310afbd-6010-586e-805d-551d846da421:b6-transport-albumin-gut-hydrolysis","predicate":"protein-binding-limits","statement":"Albumin binding inhibited hydrolysis of 2 micromolar PLP at pH 5-7.4; at pH 3-4 binding was negligible and hydrolysis persisted.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"c7dc426e-b07e-55b2-9351-af0dff931347","mechanism_event_label":"Protein binding and acidity changed substrate access.","subject":{"id":"6b656ff5-9532-5da4-8eea-8ca163a48649","slug":"pyridoxal-phosphate","display_name":"PLP","entity_type_key":"small_molecule"},"object":{"id":"15281366-8150-513d-9023-607945febb75","slug":"intestinal-plp-hydrolysis","display_name":"Intestinal PLP hydrolysis","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"c7dc426e-b07e-55b2-9351-af0dff931347","stable_key":"1310afbd-6010-586e-805d-551d846da421:b6-transport-albumin-gut-hydrolysis-event","event_type":"biochemical_relationship","label":"Protein binding and acidity changed substrate access.","description":"Albumin binding inhibited hydrolysis of 2 micromolar PLP at pH 5-7.4; at pH 3-4 binding was negligible and hydrolysis persisted.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"6b656ff5-9532-5da4-8eea-8ca163a48649","slug":"pyridoxal-phosphate","display_name":"PLP","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"15281366-8150-513d-9023-607945febb75","slug":"intestinal-plp-hydrolysis","display_name":"Intestinal PLP hydrolysis","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_location","value_text":"Indexed abstract: hydrolysis, albumin and pH experiments","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Rat jejunal perfusion and in-vitro phosphatase assays.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"2 micromolar PLP, albumin and pH manipulation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Albumin species is not assigned from the indexed abstract; no human acid-suppression outcome was measured.","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":"Rattus norvegicus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Protein binding and acidity changed substrate access.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[middleton1986] Intestinal hydrolysis of pyridoxal 5'-phosphate in vitro and in vivo in the rat. Effect of protein binding and pH. (1986). https://pubmed.ncbi.nlm.nih.gov/3721120/ DOI: 10.1016/0016-5085(86)90567-6","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Perfused jejunum and in-vitro preparations","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"f4df4e8c-b0af-5d32-931e-e75b2a898d57","evidence_kind":"source_excerpt","locator":"Lines 85-96","start_line":85,"end_line":96,"excerpt":"### b6-transport-albumin-gut-hydrolysis\nAlbumin binding inhibited hydrolysis of 2 micromolar PLP at pH 5-7.4; at pH 3-4 binding was negligible and hydrolysis persisted.\nCondition category: normal\nnutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Protein binding and acidity changed substrate access.\norganism: Rattus norvegicus\ntissue_or_cell_type: Perfused jejunum and in-vitro preparations\nexperimental_model: Rat jejunal perfusion and in-vitro phosphatase assays.\nlimitations: Albumin species is not assigned from the indexed abstract; no human acid-suppression outcome was measured.\nexposure: 2 micromolar PLP, albumin and pH manipulation.\nevidence_location: Indexed abstract: hydrolysis, albumin and pH experiments\n[middleton1986] Intestinal hydrolysis of pyridoxal 5'-phosphate in vitro and in vivo in the rat. Effect of protein binding and pH. (1986). https://pubmed.ncbi.nlm.nih.gov/3721120/ DOI: 10.1016/0016-5085(86)90567-6","model_system":"Rat jejunal perfusion and in-vitro phosphatase assays.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [middleton1986] Intestinal hydrolysis of pyridoxal 5'-phosphate in vitro and in vivo in the rat. Effect of protein binding and pH. (1986). https://pubmed.ncbi.nlm.nih.gov/3721120/ DOI: 10.1016/0016-5085(86)90567-6","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. 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