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Rat enzyme behavior is not a claim that humans cannot metabolize D2 further.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient","value_text":"Vitamin D2 and D3","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-d","display_name":"Vitamin D2 and D3","entity_type_key":"chemical_species"}},{"dimension":"nutrient_topic","value_text":"Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-d","display_name":"Vitamin D2 and D3","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Rattus norvegicus protein","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A rat enzyme experiment found different terminal breakdown products for D2 and D3.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[horst2003] Rat cytochrome P450C24 (CYP24) does not metabolize 1,25-dihydroxyvitamin D2 to calcitroic acid. (2003). https://pubmed.ncbi.nlm.nih.gov/12520527/ DOI: 10.1002/jcb.10359","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"cell-free enzyme system","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"7f2eb73e-6125-5467-89c7-cdb4a0cc30a8","evidence_kind":"source_excerpt","locator":"Lines 572-585","start_line":572,"end_line":585,"excerpt":"### vd-act-rat-cyp24-d2-boundary\nPurified rat CYP24A1 produced a C24R-hydroxylated metabolite from active D2 but no detectable calcitroic acid under conditions that generated calcitroic acid from calcitriol.\nCondition category: normal\nnutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A rat enzyme experiment found different terminal breakdown products for D2 and D3.\norganism: Rattus norvegicus protein\ntissue_or_cell_type: cell-free enzyme system\nexperimental_model: Purified rat CYP24A1 with HPLC product analysis\nlimitations: Negative detection is assay-specific. Rat enzyme behavior is not a claim that humans cannot metabolize D2 further.\nexposure: Active D2 versus D3 substrates; detailed dose/time unavailable in abstract.\ncross_nutrient: false\nevidence_location: Primary abstract, purified-enzyme HPLC results.\nnutrient: Vitamin D2 and D3\n[horst2003] Rat cytochrome P450C24 (CYP24) does not metabolize 1,25-dihydroxyvitamin D2 to calcitroic acid. (2003). https://pubmed.ncbi.nlm.nih.gov/12520527/ DOI: 10.1002/jcb.10359","model_system":"Purified rat CYP24A1 with HPLC product analysis","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [horst2003] Rat cytochrome P450C24 (CYP24) does not metabolize 1,25-dihydroxyvitamin D2 to calcitroic acid. 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