{"id":"e5c99fa4-bdcc-526f-a057-f2c24b61968b","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-ferritin-l-distinction","predicate":"lacks_intrinsic","statement":"Recombinant human L-chain ferritin lacked ferroxidase activity, although H/L assembly composition altered whole-ferritin oxidation kinetics.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"863bb643-f60d-555d-ab04-054e5b573e35","mechanism_event_label":"The heavy and light chains play different roles in the storage cage.","subject":{"id":"49a7bb74-d48a-5ab8-969d-785c2a2e9655","slug":"ftl","display_name":"Human ferritin light chain / FTL","entity_type_key":"protein"},"object":{"id":"707f00a3-e5b6-597b-89b0-c5c285e809ab","slug":"ferritin-ferroxidase-activity","display_name":"Ferritin ferroxidase activity","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"863bb643-f60d-555d-ab04-054e5b573e35","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-ferritin-l-distinction-event","event_type":"biochemical_relationship","label":"The heavy and light chains play different roles in the storage cage.","description":"Recombinant human L-chain ferritin lacked ferroxidase activity, although H/L assembly composition altered whole-ferritin oxidation kinetics.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"05e98c8a-c341-5856-971a-5a7001db7fed","slug":"fth1","display_name":"Ferritin heavy chain","entity_type_key":"protein"},"role":"catalytic_partner","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"49a7bb74-d48a-5ab8-969d-785c2a2e9655","slug":"ftl","display_name":"Human ferritin light chain / FTL","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"707f00a3-e5b6-597b-89b0-c5c285e809ab","slug":"ferritin-ferroxidase-activity","display_name":"Ferritin ferroxidase activity","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"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":"Purified recombinant subunits; H/L assembly kinetics do 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":"The heavy and light chains play different roles in the storage cage.","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":"44cd370e-c666-57df-9ed7-b81feae0e651","evidence_kind":"source_excerpt","locator":"Lines 628-639","start_line":628,"end_line":639,"excerpt":"### iron-ferritin-l-distinction\nRecombinant human L-chain ferritin lacked ferroxidase activity, although H/L assembly composition altered whole-ferritin oxidation kinetics.\nCondition category: normal\nnutrient_topic: Iron research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The heavy and light chains play different roles in the storage cage.\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: Purified recombinant subunits; H/L assembly kinetics do 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. 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