{"id":"21e246fe-f486-54fc-90fc-9825d154e909","stable_key":"6d38d43e-01e4-5641-93be-65654271e242:zinc-enz-ca2-removal","predicate":"has_reduced_activity_relative_to","statement":"Chelating zinc from recombinant human CA2 reduced catalytic activity; the apo preparation retained about 10% residual zinc.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"5aae9964-594e-5d32-a9ca-204cd14fd250","mechanism_event_label":"Removing the bound zinc largely disables CA2, even though the protein is still present.","subject":{"id":"4ce171c9-c071-5fad-a0af-9a92beb88fe3","slug":"ca2-apo-chelated","display_name":"Zinc-depleted human CA2 prepared by chelation","entity_type_key":"protein_state"},"object":{"id":"812cb56b-2561-5f29-98ec-4b8cc7f79a63","slug":"ca2","display_name":"Human carbonic anhydrase II / CA2","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"5aae9964-594e-5d32-a9ca-204cd14fd250","stable_key":"6d38d43e-01e4-5641-93be-65654271e242:zinc-enz-ca2-removal-event","event_type":"biochemical_relationship","label":"Removing the bound zinc largely disables CA2, even though the protein is still present.","description":"Chelating zinc from recombinant human CA2 reduced catalytic activity; the apo preparation retained about 10% residual zinc.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"49c806c2-7041-5020-8b3b-fa04ffa122ac","slug":"zinc-ion","display_name":"Zinc(II) ion","entity_type_key":"ion"},"role":"removed_cofactor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"4ce171c9-c071-5fad-a0af-9a92beb88fe3","slug":"ca2-apo-chelated","display_name":"Zinc-depleted human CA2 prepared by chelation","entity_type_key":"protein_state"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"812cb56b-2561-5f29-98ec-4b8cc7f79a63","slug":"ca2","display_name":"Human carbonic anhydrase II / CA2","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified recombinant human CA2 expressed in E. coli; chelation, crystallography, DSC and H/D exchange","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"100 mM pyridine-2,6-dicarboxylic acid, 25 mM MOPS pH 7.0, 20°C for 8 h; chelator removed by buffer exchange.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Purified recombinant protein; chelation is not dietary deficiency. Approximately 10% zinc remained in the nominal apo preparation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Zinc research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"zinc","display_name":"Zinc","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Removing the bound zinc largely disables CA2, even though the protein is still present.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[zinc-enz-ca2-apo2009] Apo-human carbonic anhydrase II revisited: implications of the loss of a metal in protein structure, stability, and solvent network. (2009). https://pubmed.ncbi.nlm.nih.gov/19583303/ DOI: 10.1021/bi9007512","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified protein; cell-free assay","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"8fedbd6f-685e-5263-b9c3-bfbff4c5d8bb","evidence_kind":"source_excerpt","locator":"Lines 599-610","start_line":599,"end_line":610,"excerpt":"### zinc-enz-ca2-removal\nChelating zinc from recombinant human CA2 reduced catalytic activity; the apo preparation retained about 10% residual zinc.\nCondition category: normal\nnutrient_topic: Zinc research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Removing the bound zinc largely disables CA2, even though the protein is still present.\norganism: Homo sapiens\ntissue_or_cell_type: Purified protein; cell-free assay\nexperimental_model: Purified recombinant human CA2 expressed in E. coli; chelation, crystallography, DSC and H/D exchange\nlimitations: Purified recombinant protein; chelation is not dietary deficiency. Approximately 10% zinc remained in the nominal apo preparation.\nexposure: 100 mM pyridine-2,6-dicarboxylic acid, 25 mM MOPS pH 7.0, 20°C for 8 h; chelator removed by buffer exchange.\ncross_nutrient: false\n[zinc-enz-ca2-apo2009] Apo-human carbonic anhydrase II revisited: implications of the loss of a metal in protein structure, stability, and solvent network. (2009). https://pubmed.ncbi.nlm.nih.gov/19583303/ DOI: 10.1021/bi9007512","model_system":"Purified recombinant human CA2 expressed in E. coli; chelation, crystallography, DSC and H/D exchange","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [zinc-enz-ca2-apo2009] Apo-human carbonic anhydrase II revisited: implications of the loss of a metal in protein structure, stability, and solvent network. (2009). https://pubmed.ncbi.nlm.nih.gov/19583303/ DOI: 10.1021/bi9007512","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"c5ee0fee-ce5c-58de-905a-10fb0ea0723c","stable_key":"import-6d38d43e-01e4-5641-93be-65654271e242","title":"Zinc: transport, enzyme loading, deficiency 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":"2e731dd54477ec1254e97df3323e1208d38f1375effed19252e71ab4f600d13a","revision_id":"c72258b9-ac09-5408-9d44-a921ad1f96a3","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}