{"id":"487fc60a-57e3-589d-b485-dda657abe91a","stable_key":"6612c190-1948-5bcf-bbe3-a7f6c50fa3cf:l-proline-pepd-manganese","predicate":"coordinates_active_site_of","statement":"Human prolidase structures contain a binuclear manganese active site associated with the hydrolytic reaction; the study proposes hydroxide as the attacking catalytic species.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"4ec634c7-1e8a-5e87-8fab-c3e32ef9955c","mechanism_event_label":"A mineral is part of the machinery that recycles proline from dipeptides.","subject":{"id":"a8082b11-c484-5792-bb81-48e8e699cbe4","slug":"manganese-ion","display_name":"Mn2+","entity_type_key":"ion"},"object":{"id":"fe1bbc6f-5c7d-5ae9-829c-e911804c23f7","slug":"pepd","display_name":"Human prolidase / PEPD","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"4ec634c7-1e8a-5e87-8fab-c3e32ef9955c","stable_key":"6612c190-1948-5bcf-bbe3-a7f6c50fa3cf:l-proline-pepd-manganese-event","event_type":"observed_relationship","label":"A mineral is part of the machinery that recycles proline from dipeptides.","description":"Human prolidase structures contain a binuclear manganese active site associated with the hydrolytic reaction; the study proposes hydroxide as the attacking catalytic species.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"a8082b11-c484-5792-bb81-48e8e699cbe4","slug":"manganese-ion","display_name":"Mn2+","entity_type_key":"ion"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"fe1bbc6f-5c7d-5ae9-829c-e911804c23f7","slug":"pepd","display_name":"Human prolidase / PEPD","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"70ccd53c-83ad-5251-a4f5-6370973bc40a","slug":"l-proline","display_name":"L-Proline","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract and linked primary deposited structure 5M4G","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human enzyme crystal structures, including deposited structure 5M4G at 1.48 angstroms.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Structural metal dependence does not establish that adding manganese improves recycling when manganese is already adequate.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Proline collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-proline","display_name":"L-Proline","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"A mineral is part of the machinery that recycles proline from dipeptides.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Substrate specificity and reaction mechanism of human prolidase. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28677335/ · DOI 10.1111/febs.14158","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"9f4f4ba6-08b0-56f3-b21b-92c43f82c29f","evidence_kind":"source_excerpt","locator":"Lines 270-276","start_line":270,"end_line":276,"excerpt":"## l-proline-pepd-manganese\nA mineral is part of the machinery that recycles proline from dipeptides.\nHuman prolidase structures contain a binuclear manganese active site associated with the hydrolytic reaction; the study proposes hydroxide as the attacking catalytic species.\nModel: Human enzyme crystal structures, including deposited structure 5M4G at 1.48 angstroms.\nLimitations: Structural metal dependence does not establish that adding manganese improves recycling when manganese is already adequate.\nEvidence access: Primary abstract and linked primary deposited structure 5M4G\nSubstrate specificity and reaction mechanism of human prolidase. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28677335/ · DOI 10.1111/febs.14158","model_system":"Human enzyme crystal structures, including deposited structure 5M4G at 1.48 angstroms.","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":"e5aa7fc5-ee52-5376-8169-416082a89fd1","stable_key":"import-6612c190-1948-5bcf-bbe3-a7f6c50fa3cf","title":"L-Proline: synthesis, collagen processing, redox 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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