{"id":"fcdbc00a-337a-590a-b00b-086988389cd2","stable_key":"a8baf7e9-80e4-5d8c-adec-9a63e84d2f21:l-cysteine-sam-sulfur-partition","predicate":"changes_predicted_cbs_contribution","statement":"Kinetic simulations predicted that SAM-dependent activation changes the relative CBS contribution to H2S generation at specified substrate concentrations.","claim_class":"hypothesis_link","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"635709bb-7c99-5709-9541-249ab786fdda","mechanism_event_label":"Methylation-cycle chemistry can influence a sulfur-signaling branch.","subject":{"id":"825f2da2-01bc-5874-a3c6-64f5ac867db5","slug":"s-adenosylmethionine","display_name":"S-Adenosyl-L-methionine","entity_type_key":"small_molecule"},"object":{"id":"4688e32c-d7b6-5fca-9eb2-23307c29ae07","slug":"cbs","display_name":"Human cystathionine beta-synthase / CBS","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"635709bb-7c99-5709-9541-249ab786fdda","stable_key":"a8baf7e9-80e4-5d8c-adec-9a63e84d2f21:l-cysteine-sam-sulfur-partition-event","event_type":"observed_relationship","label":"Methylation-cycle chemistry can influence a sulfur-signaling branch.","description":"Kinetic simulations predicted that SAM-dependent activation changes the relative CBS contribution to H2S generation at specified substrate concentrations.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"825f2da2-01bc-5874-a3c6-64f5ac867db5","slug":"s-adenosylmethionine","display_name":"S-Adenosyl-L-methionine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"4688e32c-d7b6-5fca-9eb2-23307c29ae07","slug":"cbs","display_name":"Human cystathionine beta-synthase / CBS","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":"70cc3ced-8adc-5e76-9750-e1415683455b","slug":"hydrogen-sulfide","display_name":"Hydrogen sulfide / H2S","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"4014ee3a-0e44-5379-b541-174aa75bcf90","slug":"cth","display_name":"Human cystathionine gamma-lyase / CTH","entity_type_key":"protein"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"5b635b42-bc0d-5c54-aa94-9cf76cd0ed47","slug":"homocysteine","display_name":"Homocysteine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Simulation based on purified CBS/CSE kinetics with assumed equimolar enzyme concentrations.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"A modeled 25–70% contribution is not a directly measured universal human tissue fraction.","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":"Methylation-cycle chemistry can influence a sulfur-signaling branch.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Relative contributions of cystathionine beta-synthase and gamma-cystathionase to H2S biogenesis via alternative trans-sulfuration reactions. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19531479/ · DOI 10.1074/jbc.M109.010868","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"983632e3-5b52-5110-868b-39e18f36f282","evidence_kind":"source_excerpt","locator":"Lines 292-298","start_line":292,"end_line":298,"excerpt":"## l-cysteine-sam-sulfur-partition\nMethylation-cycle chemistry can influence a sulfur-signaling branch.\nKinetic simulations predicted that SAM-dependent activation changes the relative CBS contribution to H2S generation at specified substrate concentrations.\nModel: Simulation based on purified CBS/CSE kinetics with assumed equimolar enzyme concentrations.\nLimitations: A modeled 25–70% contribution is not a directly measured universal human tissue fraction.\nEvidence access: Primary abstract\nRelative contributions of cystathionine beta-synthase and gamma-cystathionase to H2S biogenesis via alternative trans-sulfuration reactions. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19531479/ · DOI 10.1074/jbc.M109.010868","model_system":"Simulation based on purified CBS/CSE kinetics with assumed equimolar enzyme concentrations.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; 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