{"id":"e7574f41-24f6-5333-a6a3-5fdd02a8bd4f","stable_key":"a8baf7e9-80e4-5d8c-adec-9a63e84d2f21:l-cysteine-mpst-thioredoxin-inhibition","predicate":"regulates","statement":"Thioredoxin showed substrate inhibition in human MPST assays and increased the apparent Km for 3-mercaptopyruvate relative to other acceptors.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"fb5efb2d-3218-5c81-a486-ae4baea0d5a9","mechanism_event_label":"More of a redox partner did not simply produce a faster reaction.","subject":{"id":"ef19a1dc-9098-5e4e-99e1-2e1cd0daf283","slug":"thioredoxin","display_name":"Thioredoxin / TXN","entity_type_key":"protein"},"object":{"id":"bd69cbdf-a220-5981-b89f-c31b53f25f40","slug":"mpst","display_name":"Human mercaptopyruvate sulfurtransferase / MPST","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"fb5efb2d-3218-5c81-a486-ae4baea0d5a9","stable_key":"a8baf7e9-80e4-5d8c-adec-9a63e84d2f21:l-cysteine-mpst-thioredoxin-inhibition-event","event_type":"observed_relationship","label":"More of a redox partner did not simply produce a faster reaction.","description":"Thioredoxin showed substrate inhibition in human MPST assays and increased the apparent Km for 3-mercaptopyruvate relative to other acceptors.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"ef19a1dc-9098-5e4e-99e1-2e1cd0daf283","slug":"thioredoxin","display_name":"Thioredoxin / TXN","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"bd69cbdf-a220-5981-b89f-c31b53f25f40","slug":"mpst","display_name":"Human mercaptopyruvate sulfurtransferase / MPST","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"ca899f13-50ad-55e5-ab99-329ae0038c74","slug":"l-cysteine","display_name":"L-Cysteine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"fd727c98-d9db-5c94-9fc3-8f7c6f8272df","slug":"3-mercaptopyruvate","display_name":"3-Mercaptopyruvate","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"b08835d2-3c24-52dd-b9b9-a1d34c28b14f","slug":"human-mpst-enzyme-persulfide","display_name":"Human MPST active-site cysteine persulfide","entity_type_key":"cellular_process"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant human MPST isoform kinetics.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Predicted tissue sulfur allocation was based on simulations; no human dietary response was measured.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Cysteine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-cysteine","display_name":"L-Cysteine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"More of a redox partner did not simply produce a faster reaction.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Thioredoxin regulates human mercaptopyruvate sulfurtransferase at physiologically-relevant concentrations. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32179647/ · DOI 10.1074/jbc.RA120.012616","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"22c3f4b0-0fcf-5edf-954b-82bc26b184b8","evidence_kind":"source_excerpt","locator":"Lines 468-474","start_line":468,"end_line":474,"excerpt":"## l-cysteine-mpst-thioredoxin-inhibition\nMore of a redox partner did not simply produce a faster reaction.\nThioredoxin showed substrate inhibition in human MPST assays and increased the apparent Km for 3-mercaptopyruvate relative to other acceptors.\nModel: Recombinant human MPST isoform kinetics.\nLimitations: Predicted tissue sulfur allocation was based on simulations; no human dietary response was measured.\nEvidence access: Primary abstract\nThioredoxin regulates human mercaptopyruvate sulfurtransferase at physiologically-relevant concentrations. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32179647/ · DOI 10.1074/jbc.RA120.012616","model_system":"Recombinant human MPST isoform kinetics.","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":"654560f6-8d7f-596b-8722-48d94053cfe3","stable_key":"import-a8baf7e9-80e4-5d8c-adec-9a63e84d2f21","title":"L-Cysteine: sulfur allocation, redox supply 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":"f722669e54eab08ffe7289f9d79ddfc443014ed8c4bc5ba10ce2635470d22498","revision_id":"8ae25609-a031-5782-9c62-6cad8767ea46","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}