{"id":"fa8bac84-b303-57e2-b358-4ef9e3d1866f","stable_key":"dc8975b1-95ff-5d9b-be17-a1c04610cca7:mo-mocs1a-oxygen","predicate":"degrades_clusters_in_purified","statement":"Oxygen rapidly degraded both reconstituted MOCS1A [4Fe-4S] clusters, producing different semistable cluster intermediates.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"02fad2b2-d1f9-5026-9f51-2359be8d0b47","mechanism_event_label":"The assembly protein contains oxygen-sensitive clusters.","subject":{"id":"899c7ab0-6f81-5b38-a6bd-fbb33d66ac8d","slug":"oxygen","display_name":"Molecular oxygen","entity_type_key":"small_molecule"},"object":{"id":"33975f8e-c4ce-5122-8969-8fa35a8d009d","slug":"mocs1a","display_name":"Human molybdenum cofactor synthesis protein MOCS1A","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"02fad2b2-d1f9-5026-9f51-2359be8d0b47","stable_key":"dc8975b1-95ff-5d9b-be17-a1c04610cca7:mo-mocs1a-oxygen-event","event_type":"biochemical_relationship","label":"The assembly protein contains oxygen-sensitive clusters.","description":"Oxygen rapidly degraded both reconstituted MOCS1A [4Fe-4S] clusters, producing different semistable cluster intermediates.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"8058ae47-b091-5004-ba65-1e50ad91f70b","slug":"iron-sulfur-4fe4s","display_name":"[4Fe-4S] iron-sulfur cluster","entity_type_key":"chemical_species"},"role":"starting cofactor","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":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"33975f8e-c4ce-5122-8969-8fa35a8d009d","slug":"mocs1a","display_name":"Human molybdenum cofactor synthesis protein MOCS1A","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/molybdenum-research/15180982.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"722c11f1c29a720fb7105f37962af2652ce95b6734afdb59d675dee0b8302097\", \"start_char\": 0, \"end_char\": 1828, \"text_sha256\": \"722c11f1c29a720fb7105f37962af2652ce95b6734afdb59d675dee0b8302097\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant human MOCS1A, cysteine mutagenesis and multiple spectroscopic methods","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Aerobic versus anaerobic purification; iron-sulfur reconstitution","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Purified protein exposure; not evidence that normal breathing causes cofactor deficiency.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Molybdenum research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"molybdenum","display_name":"Molybdenum","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Human protein expressed in Escherichia coli","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The assembly protein contains oxygen-sensitive clusters.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[mo-p15180982] Characterization of MOCS1A, an oxygen-sensitive iron-sulfur protein involved in human molybdenum cofactor biosynthesis. (2004). https://pubmed.ncbi.nlm.nih.gov/15180982/ DOI: 10.1074/jbc.m313398200","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified protein and bacterial complementation","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"62857e15-9cac-5a34-ad9a-3705273f6872","evidence_kind":"source_excerpt","locator":"Lines 339-350","start_line":339,"end_line":350,"excerpt":"### mo-mocs1a-oxygen\nOxygen rapidly degraded both reconstituted MOCS1A [4Fe-4S] clusters, producing different semistable cluster intermediates.\nCondition category: normal\nnutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The assembly protein contains oxygen-sensitive clusters.\norganism: Human protein expressed in Escherichia coli\ntissue_or_cell_type: Purified protein and bacterial complementation\nexperimental_model: Recombinant human MOCS1A, cysteine mutagenesis and multiple spectroscopic methods\nlimitations: Purified protein exposure; not evidence that normal breathing causes cofactor deficiency.\nexposure: Aerobic versus anaerobic purification; iron-sulfur reconstitution\nevidence_span: {\"source_cache\": \"artifacts/molybdenum-research/15180982.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"722c11f1c29a720fb7105f37962af2652ce95b6734afdb59d675dee0b8302097\", \"start_char\": 0, \"end_char\": 1828, \"text_sha256\": \"722c11f1c29a720fb7105f37962af2652ce95b6734afdb59d675dee0b8302097\"}\n[mo-p15180982] Characterization of MOCS1A, an oxygen-sensitive iron-sulfur protein involved in human molybdenum cofactor biosynthesis. (2004). https://pubmed.ncbi.nlm.nih.gov/15180982/ DOI: 10.1074/jbc.m313398200","model_system":"Recombinant human MOCS1A, cysteine mutagenesis and multiple spectroscopic methods","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [mo-p15180982] Characterization of MOCS1A, an oxygen-sensitive iron-sulfur protein involved in human molybdenum cofactor biosynthesis. (2004). https://pubmed.ncbi.nlm.nih.gov/15180982/ DOI: 10.1074/jbc.m313398200","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"1aa6da60-8284-5252-8dd9-ac2250d5ced5","stable_key":"import-dc8975b1-95ff-5d9b-be17-a1c04610cca7","title":"Molybdenum: cofactor assembly, sulfur metabolism 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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