{"id":"ebceaa34-b415-5c04-99e7-8903371805a6","stable_key":"63ce713e-6aea-59f6-9896-ca30e010b2ce:l-tyrosine-tyr-dopa","predicate":"produces","statement":"Purified recombinant human tyrosinase showed monophenolase activity with L-tyrosine, the initial hydroxylation step toward pigment.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"5e1aafc0-b205-591e-94d0-87b83221bc19","mechanism_event_label":"A different enzyme uses the same amino acid for pigment chemistry.","subject":{"id":"d1ee71a8-af1f-5a6f-a879-e75134fa12af","slug":"tyr","display_name":"Human tyrosinase / TYR","entity_type_key":"protein"},"object":{"id":"d2e54a66-7f3c-5bcc-adbe-9f66ad4264f4","slug":"l-dopa","display_name":"L-3,4-Dihydroxyphenylalanine","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"5e1aafc0-b205-591e-94d0-87b83221bc19","stable_key":"63ce713e-6aea-59f6-9896-ca30e010b2ce:l-tyrosine-tyr-dopa-event","event_type":"observed_relationship","label":"A different enzyme uses the same amino acid for pigment chemistry.","description":"Purified recombinant human tyrosinase showed monophenolase activity with L-tyrosine, the initial hydroxylation step toward pigment.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"d1ee71a8-af1f-5a6f-a879-e75134fa12af","slug":"tyr","display_name":"Human tyrosinase / TYR","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"d2e54a66-7f3c-5bcc-adbe-9f66ad4264f4","slug":"l-dopa","display_name":"L-3,4-Dihydroxyphenylalanine","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"bcfef85f-831d-5439-ba51-1aef4b090441","slug":"l-tyrosine","display_name":"L-Tyrosine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"9f0afdde-1ec1-5c8a-bb5e-f3b2b75f67f6","slug":"copper","display_name":"Copper","entity_type_key":"nutrient_element"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"899c7ab0-6f81-5b38-a6bd-fbb33d66ac8d","slug":"oxygen","display_name":"Molecular oxygen","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; Results and catalytic assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human intramelanosomal domain expressed in insect cells; activity assays.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Same metabolite identity as L-DOPA in catecholamine synthesis, but different enzyme and compartment.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Tyrosine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-tyrosine","display_name":"L-Tyrosine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"A different enzyme uses the same amino acid for pigment chemistry.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Albinism-causing mutations in recombinant human tyrosinase alter intrinsic enzymatic activity. · 2014 · https://pubmed.ncbi.nlm.nih.gov/24392141/ · DOI 10.1371/journal.pone.0084494","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"5ca62244-6e7d-5351-9f80-04dd82b1f3a2","evidence_kind":"source_excerpt","locator":"Lines 148-154","start_line":148,"end_line":154,"excerpt":"## l-tyrosine-tyr-dopa\nA different enzyme uses the same amino acid for pigment chemistry.\nPurified recombinant human tyrosinase showed monophenolase activity with L-tyrosine, the initial hydroxylation step toward pigment.\nModel: Human intramelanosomal domain expressed in insect cells; activity assays.\nLimitations: Same metabolite identity as L-DOPA in catecholamine synthesis, but different enzyme and compartment.\nEvidence access: Primary full text; Results and catalytic assays\nAlbinism-causing mutations in recombinant human tyrosinase alter intrinsic enzymatic activity. · 2014 · https://pubmed.ncbi.nlm.nih.gov/24392141/ · DOI 10.1371/journal.pone.0084494","model_system":"Human intramelanosomal domain expressed in insect cells; activity assays.","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":"12917df2-c6e0-5b61-850f-dbff6d4b4d30","stable_key":"import-63ce713e-6aea-59f6-9896-ca30e010b2ce","title":"L-Tyrosine: catecholamines, thyroid chemistry, pigment, metabolism 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. 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