{"id":"16ae788c-33d9-5695-be12-777278b56470","stable_key":"911fb3c7-8cc3-5667-b677-5682fab67648:histidine-skin-ph-redundancy","predicate":"is_not_sole_requirement_for","statement":"Histidase-deficient Peruvian mice retained skin-surface pH similar to matched controls.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"12037374-a126-55fc-9aae-2c6c8ba2ddd3","mechanism_event_label":"Other systems could preserve skin acidity when this histidine-processing enzyme was absent.","subject":{"id":"68ce4cd6-40f6-567e-84f3-0b03f2b9e1bb","slug":"mouse-hal","display_name":"Mouse histidine ammonia-lyase / Hal","entity_type_key":"protein"},"object":{"id":"81b1a11a-7741-5b60-8a64-129ef60ce6b9","slug":"mouse-stratum-corneum-acidity","display_name":"Mouse stratum-corneum surface acidity","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"12037374-a126-55fc-9aae-2c6c8ba2ddd3","stable_key":"911fb3c7-8cc3-5667-b677-5682fab67648:histidine-skin-ph-redundancy-event","event_type":"observed_relationship","label":"Other systems could preserve skin acidity when this histidine-processing enzyme was absent.","description":"Histidase-deficient Peruvian mice retained skin-surface pH similar to matched controls.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"68ce4cd6-40f6-567e-84f3-0b03f2b9e1bb","slug":"mouse-hal","display_name":"Mouse histidine ammonia-lyase / Hal","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"81b1a11a-7741-5b60-8a64-129ef60ce6b9","slug":"mouse-stratum-corneum-acidity","display_name":"Mouse stratum-corneum surface acidity","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"44374451-3436-5136-a8ae-5dcc6d8c353b","slug":"histidine","display_name":"L-Histidine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"evidence_access","value_text":"Primary full text","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Mouse histidase-deficiency comparison; surface pH measurement.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Does not negate urocanate chemistry or human skin-equivalent effects; distinct endpoint, species and manipulation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Histidine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"histidine","display_name":"L-Histidine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"Other systems could preserve skin acidity when this histidine-processing enzyme was absent.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Is the filaggrin-histidine-urocanic acid pathway essential for stratum corneum acidification? · 2010 · https://pubmed.ncbi.nlm.nih.gov/20376063/ · DOI 10.1038/jid.2010.74","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":"ddea5de9-c7fa-5fbf-b47a-23af5c83aec7","evidence_kind":"source_excerpt","locator":"Lines 442-448","start_line":442,"end_line":448,"excerpt":"## histidine-skin-ph-redundancy\nOther systems could preserve skin acidity when this histidine-processing enzyme was absent.\nHistidase-deficient Peruvian mice retained skin-surface pH similar to matched controls.\nModel: Mouse histidase-deficiency comparison; surface pH measurement.\nLimitations: Does not negate urocanate chemistry or human skin-equivalent effects; distinct endpoint, species and manipulation.\nEvidence access: Primary full text\nIs the filaggrin-histidine-urocanic acid pathway essential for stratum corneum acidification? 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