{"id":"a5d00e24-d7ed-5285-9043-4080602795e1","stable_key":"ae1ed35d-8ce7-5936-9067-a641374bbf79:carnosine-proton-buffer","predicate":"reversibly_binds","statement":"NMR and potentiometric titration measured reversible protonation of carnosine, including its imidazole site near physiological pH.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"1fbce595-fad1-52b7-b311-1526fc7fe760","mechanism_event_label":"Reversible proton binding gives the molecule buffering capacity.","subject":{"id":"9998eb9b-0d09-58c9-885b-a442477dec8d","slug":"carnosine","display_name":"L-Carnosine / beta-alanyl-L-histidine","entity_type_key":"small_molecule"},"object":{"id":"16a9848a-023b-5828-9fd1-e28b9eadb901","slug":"hydrogen-ion","display_name":"Hydrogen ion","entity_type_key":"ion"},"evidence_count":1,"mechanism_event":{"id":"1fbce595-fad1-52b7-b311-1526fc7fe760","stable_key":"ae1ed35d-8ce7-5936-9067-a641374bbf79:carnosine-proton-buffer-event","event_type":"observed_relationship","label":"Reversible proton binding gives the molecule buffering capacity.","description":"NMR and potentiometric titration measured reversible protonation of carnosine, including its imidazole site near physiological pH.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"9998eb9b-0d09-58c9-885b-a442477dec8d","slug":"carnosine","display_name":"L-Carnosine / beta-alanyl-L-histidine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"16a9848a-023b-5828-9fd1-e28b9eadb901","slug":"hydrogen-ion","display_name":"Hydrogen ion","entity_type_key":"ion"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full text, methods and protonation results","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified dipeptides at 310.15 K and 0.15 M ionic strength.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Chemical buffering does not establish how much a supplement changes exercising muscle pH.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"carnosine","display_name":"L-Carnosine / beta-alanyl-L-histidine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"Reversible proton binding gives the molecule buffering capacity.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Species-specific acid-base characterization of carnosine and homocarnosine using nuclear magnetic resonance · 2022 · https://doi.org/10.1016/j.cplett.2022.140128 · DOI 10.1016/j.cplett.2022.140128","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"a6a832e8-30a3-5985-bb2b-e655980961a1","evidence_kind":"source_excerpt","locator":"Lines 180-186","start_line":180,"end_line":186,"excerpt":"## carnosine-proton-buffer\nReversible proton binding gives the molecule buffering capacity.\nNMR and potentiometric titration measured reversible protonation of carnosine, including its imidazole site near physiological pH.\nModel: Purified dipeptides at 310.15 K and 0.15 M ionic strength.\nLimitations: Chemical buffering does not establish how much a supplement changes exercising muscle pH.\nEvidence access: Primary full text, methods and protonation results\nSpecies-specific acid-base characterization of carnosine and homocarnosine using nuclear magnetic resonance · 2022 · https://doi.org/10.1016/j.cplett.2022.140128 · DOI 10.1016/j.cplett.2022.140128","model_system":"Purified dipeptides at 310.15 K and 0.15 M ionic strength.","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":"87dc5af2-4eb6-5980-b7e0-bf3697b1156e","stable_key":"import-ae1ed35d-8ce7-5936-9067-a641374bbf79","title":"Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text.","file_path":"","sha256":"469cbc38203db56bd031f9d8a2dd2bfa387713950ca30199511cd137e927aa7a","revision_id":"cc409a15-8b04-50ee-a7ff-d1bf32f686bb","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}