{"id":"a3591c91-dc0b-5647-912e-809451faa5c9","stable_key":"1310afbd-6010-586e-805d-551d846da421:b6-met-rabbit-phosphorylase-phosphate","predicate":"supports-catalysis-by","statement":"A labeled cofactor-analogue experiment supported direct participation of the PLP phosphate group in glycogen phosphorylase glucosyl transfer.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"844d4975-3146-578b-b31f-ff79416e7ffb","mechanism_event_label":"The phosphate portion of active B6 helps this carbohydrate reaction.","subject":{"id":"6b656ff5-9532-5da4-8eea-8ca163a48649","slug":"pyridoxal-phosphate","display_name":"PLP","entity_type_key":"small_molecule"},"object":{"id":"5a1cc7d4-ac45-5843-9f0a-a13b051fb686","slug":"rabbit-pygm","display_name":"Rabbit skeletal-muscle glycogen phosphorylase","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"844d4975-3146-578b-b31f-ff79416e7ffb","stable_key":"1310afbd-6010-586e-805d-551d846da421:b6-met-rabbit-phosphorylase-phosphate-event","event_type":"biochemical_relationship","label":"The phosphate portion of active B6 helps this carbohydrate reaction.","description":"A labeled cofactor-analogue experiment supported direct participation of the PLP phosphate group in glycogen phosphorylase glucosyl transfer.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"5a1cc7d4-ac45-5843-9f0a-a13b051fb686","slug":"rabbit-pygm","display_name":"Rabbit skeletal-muscle glycogen phosphorylase","entity_type_key":"protein"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"6b656ff5-9532-5da4-8eea-8ca163a48649","slug":"pyridoxal-phosphate","display_name":"PLP","entity_type_key":"small_molecule"},"role":"native cofactor represented by analogue","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"05c4c656-fd3f-55da-850b-3eea7fb0bc4b","slug":"glycogen","display_name":"Glycogen","entity_type_key":"chemical_species"},"role":"glucosyl acceptor","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"4c77dafc-3257-5fca-8d67-6d7672a11351","slug":"glucose-1-phosphate","display_name":"alpha-D-Glucose 1-phosphate","entity_type_key":"small_molecule"},"role":"native phosphoryl substrate/product","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"PLP-phosphate chemistry supports glycogen metabolism.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Rabbit muscle phosphorylase reconstituted with synthetic cofactor analogue","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Synthetic pyridoxal-diphospho-glucose analogue reconstitution","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Mechanistic analogue evidence; not a demonstration of muscle glycogen failure in human B6 deficiency.","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":"Oryctolagus cuniculus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The phosphate portion of active B6 helps this carbohydrate reaction.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[b6-phosphorylase-1982] Catalytic mechanism of glycogen phosphorylase: pyridoxal(5')diphospho(1)-alpha-D-glucose as a transition-state analogue. (1982). https://pmc.ncbi.nlm.nih.gov/articles/PMC346497/ DOI: 10.1073/pnas.79.12.3716","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Rabbit skeletal-muscle protein","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"3221b108-41bb-5849-8867-80fa3bc0f4c6","evidence_kind":"source_excerpt","locator":"Lines 860-871","start_line":860,"end_line":871,"excerpt":"### b6-met-rabbit-phosphorylase-phosphate\nA labeled cofactor-analogue experiment supported direct participation of the PLP phosphate group in glycogen phosphorylase glucosyl transfer.\nCondition category: normal\nnutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The phosphate portion of active B6 helps this carbohydrate reaction.\norganism: Oryctolagus cuniculus\ntissue_or_cell_type: Rabbit skeletal-muscle protein\nexperimental_model: Rabbit muscle phosphorylase reconstituted with synthetic cofactor analogue\nlimitations: Mechanistic analogue evidence; not a demonstration of muscle glycogen failure in human B6 deficiency.\ncross_nutrient: PLP-phosphate chemistry supports glycogen metabolism.\nexposure: Synthetic pyridoxal-diphospho-glucose analogue reconstitution\n[b6-phosphorylase-1982] Catalytic mechanism of glycogen phosphorylase: pyridoxal(5')diphospho(1)-alpha-D-glucose as a transition-state analogue. (1982). https://pmc.ncbi.nlm.nih.gov/articles/PMC346497/ DOI: 10.1073/pnas.79.12.3716","model_system":"Rabbit muscle phosphorylase reconstituted with synthetic cofactor analogue","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [b6-phosphorylase-1982] Catalytic mechanism of glycogen phosphorylase: pyridoxal(5')diphospho(1)-alpha-D-glucose as a transition-state analogue. (1982). https://pmc.ncbi.nlm.nih.gov/articles/PMC346497/ DOI: 10.1073/pnas.79.12.3716","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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