{"id":"87f67d04-97f7-51e9-924c-b36ce4294cbd","stable_key":"584c58f5-ab9f-53f3-97a9-55783db943b0:tryptophan-ido-binding-not-catalysis","predicate":"mutations_disable_catalysis","statement":"Human IDO1 F226A, F227A and R231A mutants retained substrate binding but lacked catalytic activity.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"5c5b04ac-a23d-5553-8f0d-de9c1d8c1a4c","mechanism_event_label":"Binding the nutrient is not enough to process it.","subject":{"id":"9edba4aa-c2f5-5a4e-9750-15e9a38b1822","slug":"ido1","display_name":"Human indoleamine 2,3-dioxygenase 1 / IDO1","entity_type_key":"protein"},"object":{"id":"540784df-850e-5eac-a71c-22556535e471","slug":"n-formylkynurenine","display_name":"N-Formyl-L-kynurenine","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"5c5b04ac-a23d-5553-8f0d-de9c1d8c1a4c","stable_key":"584c58f5-ab9f-53f3-97a9-55783db943b0:tryptophan-ido-binding-not-catalysis-event","event_type":"observed_relationship","label":"Binding the nutrient is not enough to process it.","description":"Human IDO1 F226A, F227A and R231A mutants retained substrate binding but lacked catalytic activity.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"9edba4aa-c2f5-5a4e-9750-15e9a38b1822","slug":"ido1","display_name":"Human indoleamine 2,3-dioxygenase 1 / IDO1","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"540784df-850e-5eac-a71c-22556535e471","slug":"n-formylkynurenine","display_name":"N-Formyl-L-kynurenine","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"769339cb-213b-559e-acc0-07ed00368b94","slug":"l-tryptophan","display_name":"L-Tryptophan","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 abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human enzyme site-directed mutagenesis.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Engineered mutants, not a characterized common dietary disorder.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Tryptophan collection; molecular form, preparation, species, exposure and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-tryptophan","display_name":"L-Tryptophan","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"Binding the nutrient is not enough to process it.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Crystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase. · 2006 · https://pubmed.ncbi.nlm.nih.gov/16477023/ · DOI 10.1073/pnas.0508996103","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":"9c91ab40-a29d-57da-b89f-66aff4b49629","evidence_kind":"source_excerpt","locator":"Lines 178-184","start_line":178,"end_line":184,"excerpt":"## tryptophan-ido-binding-not-catalysis\nBinding the nutrient is not enough to process it.\nHuman IDO1 F226A, F227A and R231A mutants retained substrate binding but lacked catalytic activity.\nModel: Human enzyme site-directed mutagenesis.\nLimitations: Engineered mutants, not a characterized common dietary disorder.\nEvidence access: Primary abstract\nCrystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase. · 2006 · https://pubmed.ncbi.nlm.nih.gov/16477023/ · DOI 10.1073/pnas.0508996103","model_system":"Human enzyme site-directed mutagenesis.","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":"73f9d3e7-fdc9-5418-8f3c-f4ef145f6efa","stable_key":"import-584c58f5-ab9f-53f3-97a9-55783db943b0","title":"Tryptophan: transport, protein synthesis, neuroactive metabolites, NAD and microbial pathways (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary-abstract references and experimental limitations individually identified. 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