{"id":"4255208e-cb1f-5404-a57c-30b0cdb14c44","stable_key":"584c58f5-ab9f-53f3-97a9-55783db943b0:tryptophan-tnaa-hydroxyindole","predicate":"converts_alternate_substrate_to","statement":"TnaA also converted 5-HTP to 5-hydroxyindole, with lower catalytic efficiency than for tryptophan.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"168b736d-2835-5ad5-96fa-3e2fb8334df8","mechanism_event_label":"The serotonin precursor can instead become a microbial product.","subject":{"id":"692b4b36-008c-561a-be81-f953f72c49a4","slug":"e-coli-bw25113-tnaa","display_name":"Escherichia coli BW25113 tryptophanase / TnaA","entity_type_key":"protein"},"object":{"id":"3028b060-9388-575a-a012-e68003ed59e5","slug":"5-hydroxyindole","display_name":"5-Hydroxyindole","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"168b736d-2835-5ad5-96fa-3e2fb8334df8","stable_key":"584c58f5-ab9f-53f3-97a9-55783db943b0:tryptophan-tnaa-hydroxyindole-event","event_type":"observed_relationship","label":"The serotonin precursor can instead become a microbial product.","description":"TnaA also converted 5-HTP to 5-hydroxyindole, with lower catalytic efficiency than for tryptophan.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"692b4b36-008c-561a-be81-f953f72c49a4","slug":"e-coli-bw25113-tnaa","display_name":"Escherichia coli BW25113 tryptophanase / TnaA","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"3028b060-9388-575a-a012-e68003ed59e5","slug":"5-hydroxyindole","display_name":"5-Hydroxyindole","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":""},{"entity":{"id":"2400a779-1a96-58d4-b268-14ace17871e6","slug":"5-hydroxy-l-tryptophan","display_name":"5-Hydroxy-L-tryptophan","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"6b656ff5-9532-5da4-8eea-8ca163a48649","slug":"pyridoxal-phosphate","display_name":"PLP","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full text, Figure 2","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified E. coli enzyme and tnaA-mutant experiments.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"5-HTP and tryptophan are distinct substrates, not interchangeable supplement exposures.","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":"The serotonin precursor can instead become a microbial product.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Gut bacteria-derived 5-hydroxyindole is a potent stimulant of intestinal motility via its action on L-type calcium channels. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33481771/ · DOI 10.1371/journal.pbio.3001070","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"ac7d269e-54c1-5a49-b353-192bd82c3ef2","evidence_kind":"source_excerpt","locator":"Lines 642-648","start_line":642,"end_line":648,"excerpt":"## tryptophan-tnaa-hydroxyindole\nThe serotonin precursor can instead become a microbial product.\nTnaA also converted 5-HTP to 5-hydroxyindole, with lower catalytic efficiency than for tryptophan.\nModel: Purified E. coli enzyme and tnaA-mutant experiments.\nLimitations: 5-HTP and tryptophan are distinct substrates, not interchangeable supplement exposures.\nEvidence access: Primary full text, Figure 2\nGut bacteria-derived 5-hydroxyindole is a potent stimulant of intestinal motility via its action on L-type calcium channels. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33481771/ · DOI 10.1371/journal.pbio.3001070","model_system":"Purified E. coli enzyme and tnaA-mutant experiments.","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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