{"id":"a5f255e8-33d3-5893-8c32-2ad0916bf4b6","stable_key":"be889add-cec8-500b-be89-676431432a70:mn-enz-sod2-coordination","predicate":"binds","statement":"The human SOD2 active-site manganese is coordinated by His26, His74, His163, Asp159 and a water/hydroxide ligand in the structural model.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"2e03c933-0492-5b2c-a2cf-6809a54f3e1c","mechanism_event_label":"A defined protein pocket holds manganese for SOD2 chemistry.","subject":{"id":"a8082b11-c484-5792-bb81-48e8e699cbe4","slug":"manganese-ion","display_name":"Mn2+","entity_type_key":"ion"},"object":{"id":"eda566c2-d338-54b2-a872-0dd39daffcdf","slug":"sod2","display_name":"Human mitochondrial manganese superoxide dismutase / SOD2","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"2e03c933-0492-5b2c-a2cf-6809a54f3e1c","stable_key":"be889add-cec8-500b-be89-676431432a70:mn-enz-sod2-coordination-event","event_type":"biochemical_relationship","label":"A defined protein pocket holds manganese for SOD2 chemistry.","description":"The human SOD2 active-site manganese is coordinated by His26, His74, His163, Asp159 and a water/hydroxide ligand in the structural model.","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":"eda566c2-d338-54b2-a872-0dd39daffcdf","slug":"sod2","display_name":"Human mitochondrial manganese superoxide dismutase / SOD2","entity_type_key":"protein"},"role":"object","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"d31225b7-8e94-5857-9ea1-67ac794b1f15","slug":"water","display_name":"H2O","entity_type_key":"small_molecule"},"role":"metal ligand","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Redox-controlled neutron structures of human SOD2","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Redox-controlled Mn(III) and Mn(II) crystals","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Primary experimental scope only; no human dietary threshold, clinical treatment rule, or universal metal substitution is established.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Manganese research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"manganese","display_name":"Manganese","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A defined protein pocket holds manganese for SOD2 chemistry.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[mn-enz-33824320] Direct detection of coupled proton and electron transfers in human manganese superoxide dismutase. (2021). https://pubmed.ncbi.nlm.nih.gov/33824320/ DOI: 10.1038/s41467-021-22290-1","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified enzyme; mitochondrial-matrix protein","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"b73a8eb6-fa43-5995-8df0-8a090531819f","evidence_kind":"source_excerpt","locator":"Lines 434-444","start_line":434,"end_line":444,"excerpt":"### mn-enz-sod2-coordination\nThe human SOD2 active-site manganese is coordinated by His26, His74, His163, Asp159 and a water/hydroxide ligand in the structural model.\nCondition category: normal\nnutrient_topic: Manganese research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A defined protein pocket holds manganese for SOD2 chemistry.\norganism: Homo sapiens\ntissue_or_cell_type: Purified enzyme; mitochondrial-matrix protein\nexperimental_model: Redox-controlled neutron structures of human SOD2\nlimitations: Primary experimental scope only; no human dietary threshold, clinical treatment rule, or universal metal substitution is established.\nexposure: Redox-controlled Mn(III) and Mn(II) crystals\n[mn-enz-33824320] Direct detection of coupled proton and electron transfers in human manganese superoxide dismutase. (2021). https://pubmed.ncbi.nlm.nih.gov/33824320/ DOI: 10.1038/s41467-021-22290-1","model_system":"Redox-controlled neutron structures of human SOD2","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [mn-enz-33824320] Direct detection of coupled proton and electron transfers in human manganese superoxide dismutase. (2021). https://pubmed.ncbi.nlm.nih.gov/33824320/ DOI: 10.1038/s41467-021-22290-1","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"03224387-8a73-5b4f-906d-9f0be6625b7f","stable_key":"import-be889add-cec8-500b-be89-676431432a70","title":"Manganese: enzyme cofactors, glycosylation, transport and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. 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