{"id":"33d8341b-5a25-5a29-a3fa-45a54a391c63","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-ferritin-h-oxidation","predicate":"oxidizes","statement":"Human H-chain ferritin catalyzed Fe(II) oxidation; mutation of its proposed ferroxidase ligands Glu62 and His65 abolished most activity.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"ef9820c0-b18b-5c0b-a182-ea441b5481fc","mechanism_event_label":"Ferritin does chemical work to package iron, not just physical storage.","subject":{"id":"05e98c8a-c341-5856-971a-5a7001db7fed","slug":"fth1","display_name":"Ferritin heavy chain","entity_type_key":"protein"},"object":{"id":"59d6d1cd-df32-5b58-b950-3188bc7b95d6","slug":"iron-ii","display_name":"Ferrous iron","entity_type_key":"ion"},"evidence_count":1,"mechanism_event":{"id":"ef9820c0-b18b-5c0b-a182-ea441b5481fc","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-ferritin-h-oxidation-event","event_type":"biochemical_relationship","label":"Ferritin does chemical work to package iron, not just physical storage.","description":"Human H-chain ferritin catalyzed Fe(II) oxidation; mutation of its proposed ferroxidase ligands Glu62 and His65 abolished most activity.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"964be7ac-43bd-5f3e-8326-94f0590de67a","slug":"iron-iii","display_name":"Ferric iron","entity_type_key":"ion"},"role":"oxidized_form","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"899c7ab0-6f81-5b38-a6bd-fbb33d66ac8d","slug":"oxygen","display_name":"Molecular oxygen","entity_type_key":"small_molecule"},"role":"oxidant","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"05e98c8a-c341-5856-971a-5a7001db7fed","slug":"fth1","display_name":"Ferritin heavy chain","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"59d6d1cd-df32-5b58-b950-3188bc7b95d6","slug":"iron-ii","display_name":"Ferrous iron","entity_type_key":"ion"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/iron-research/8369307.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"8ccc94b97da4dcc2557e2f8ce964949b4188cd6c7e54405f6d4268ea864697ff\", \"start_char\": 0, \"end_char\": 1709, \"text_sha256\": \"8ccc94b97da4dcc2557e2f8ce964949b4188cd6c7e54405f6d4268ea864697ff\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Ferroxidase kinetics and site-directed mutants","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Fe(II) oxidation by oxygen; H-chain mutations and zinc inhibition","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"In-vitro metal concentrations and H/L composition determine kinetics; this does not establish a dietary zinc effect on human iron stores.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Iron research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"iron","display_name":"Iron","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Human recombinant ferritin and human liver apoferritin","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Ferritin does chemical work to package iron, not just physical storage.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[iron-p8369307] Ferroxidase kinetics of human liver apoferritin, recombinant H-chain apoferritin, and site-directed mutants. (1993). https://pubmed.ncbi.nlm.nih.gov/8369307/ DOI: 10.1021/bi00087a015","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified ferritin subunits/assemblies","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"51d37fa4-4a25-5865-a388-7ff10b35ef70","evidence_kind":"source_excerpt","locator":"Lines 615-626","start_line":615,"end_line":626,"excerpt":"### iron-ferritin-h-oxidation\nHuman H-chain ferritin catalyzed Fe(II) oxidation; mutation of its proposed ferroxidase ligands Glu62 and His65 abolished most activity.\nCondition category: normal\nnutrient_topic: Iron research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Ferritin does chemical work to package iron, not just physical storage.\norganism: Human recombinant ferritin and human liver apoferritin\ntissue_or_cell_type: Purified ferritin subunits/assemblies\nexperimental_model: Ferroxidase kinetics and site-directed mutants\nlimitations: In-vitro metal concentrations and H/L composition determine kinetics; this does not establish a dietary zinc effect on human iron stores.\nexposure: Fe(II) oxidation by oxygen; H-chain mutations and zinc inhibition\nevidence_span: {\"source_cache\": \"artifacts/iron-research/8369307.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"8ccc94b97da4dcc2557e2f8ce964949b4188cd6c7e54405f6d4268ea864697ff\", \"start_char\": 0, \"end_char\": 1709, \"text_sha256\": \"8ccc94b97da4dcc2557e2f8ce964949b4188cd6c7e54405f6d4268ea864697ff\"}\n[iron-p8369307] Ferroxidase kinetics of human liver apoferritin, recombinant H-chain apoferritin, and site-directed mutants. (1993). https://pubmed.ncbi.nlm.nih.gov/8369307/ DOI: 10.1021/bi00087a015","model_system":"Ferroxidase kinetics and site-directed mutants","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [iron-p8369307] Ferroxidase kinetics of human liver apoferritin, recombinant H-chain apoferritin, and site-directed mutants. (1993). https://pubmed.ncbi.nlm.nih.gov/8369307/ DOI: 10.1021/bi00087a015","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"1560864c-91d1-58dc-90c4-49bf61aba3de","stable_key":"import-e13b03e1-a614-543a-ac1b-97df18cfe30d","title":"Iron: absorption, trafficking, iron-dependent enzymes 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. Not publisher full text.","file_path":"","sha256":"f9dab767a21c9bbfef3227707fe3c82953536bb1335599dd4ef93b5ea2dbf03f","revision_id":"77700d7f-2902-54b9-adae-8cbc77b24682","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}