{"id":"81d2fc43-a102-57b8-8e70-419d0d05f789","stable_key":"649e861b-265a-5912-bc36-3a73e53ef892:l-serine-psat-plp","predicate":"forms_catalytic_cofactor_of","statement":"Human PSAT contained a PLP internal aldimine associated with Lys200; glutamate converted the cofactor toward its pyridoxamine-phosphate state during the first half-reaction.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"3d18724e-2326-5ee8-86a0-cc2f837745f8","mechanism_event_label":"The B6 cofactor cycles between forms as it carries amino-group chemistry.","subject":{"id":"6b656ff5-9532-5da4-8eea-8ca163a48649","slug":"pyridoxal-phosphate","display_name":"PLP","entity_type_key":"small_molecule"},"object":{"id":"a549bab7-965e-57f9-99b3-e8dfcb535af5","slug":"psat1","display_name":"Human phosphoserine aminotransferase / PSAT1","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"3d18724e-2326-5ee8-86a0-cc2f837745f8","stable_key":"649e861b-265a-5912-bc36-3a73e53ef892:l-serine-psat-plp-event","event_type":"observed_relationship","label":"The B6 cofactor cycles between forms as it carries amino-group chemistry.","description":"Human PSAT contained a PLP internal aldimine associated with Lys200; glutamate converted the cofactor toward its pyridoxamine-phosphate state during the first half-reaction.","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":"a549bab7-965e-57f9-99b3-e8dfcb535af5","slug":"psat1","display_name":"Human phosphoserine aminotransferase / PSAT1","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"c882cd0b-9d83-5b07-bd1c-fe4d45657dcb","slug":"l-serine","display_name":"L-Serine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"7da684a4-2641-5bc6-93ae-8c6aa384e487","slug":"glutamate","display_name":"L-Glutamate","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full text","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified human PSAT spectroscopy, substrate addition and crystallography.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"PLP is recycled in catalysis; the experiment does not show one dietary B6 molecule is consumed for each serine made.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Serine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-serine","display_name":"L-Serine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"The B6 cofactor cycles between forms as it carries amino-group chemistry.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"L-serine biosynthesis in the human central nervous system: Structure and function of phosphoserine aminotransferase. · 2023 · https://pubmed.ncbi.nlm.nih.gov/36851825/ · DOI 10.1002/pro.4609","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"41b02ede-eb22-58bd-ae49-e715ae9687e1","evidence_kind":"source_excerpt","locator":"Lines 38-44","start_line":38,"end_line":44,"excerpt":"## l-serine-psat-plp\nThe B6 cofactor cycles between forms as it carries amino-group chemistry.\nHuman PSAT contained a PLP internal aldimine associated with Lys200; glutamate converted the cofactor toward its pyridoxamine-phosphate state during the first half-reaction.\nModel: Purified human PSAT spectroscopy, substrate addition and crystallography.\nLimitations: PLP is recycled in catalysis; the experiment does not show one dietary B6 molecule is consumed for each serine made.\nEvidence access: Primary full text\nL-serine biosynthesis in the human central nervous system: Structure and function of phosphoserine aminotransferase. · 2023 · https://pubmed.ncbi.nlm.nih.gov/36851825/ · DOI 10.1002/pro.4609","model_system":"Purified human PSAT spectroscopy, substrate addition and crystallography.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"70bcf57a-36bb-563f-9073-2d616e5f155a","stable_key":"import-649e861b-265a-5912-bc36-3a73e53ef892","title":"L-Serine: synthesis, one-carbon metabolism, lipids and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text.","file_path":"","sha256":"22a750ce2b94f8607268c58322c48c4f0468f403b72a4008307538a6e5ff86d5","revision_id":"c1d6a7e1-9558-5bc6-9e3b-7080c26d3dbc","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}