title: Rat CYP24 catalyses 23S-hydroxylation of 26,26,26,27,27,27-hexafluorocalcitriol in vitro.
abstract: 1. Kidney mitochondrial 24-hydroxylase cytochrome P450 (CYP24) catalyses sequential hydroxylation at both C-24 and C-23 positions of calcidiol and calcitriol. Here, we have investigated the in vitro metabolism of a hexafluorinated derivative of calcitriol, 26,26,26,27,27,27-hexafluorocalcitriol (ST-630), in a reconstituted system by using recombinant Escherichia coli membrane fractions containing rat CYP24. 2. When ST-630 was incubated with CYP24 supplemented with bovine adrenodoxin and NADPH-adrenodoxin reductase, a distinct metabolite could be observed. This metabolite was found to be 26,26,26,27,27,27-hexafluoro-23S-hydroxcalcitriol, a biologically active metabolite of ST-630, based on cochromatography on HPLC and mass spectrometric analysis. 3. These results show the direct evidence that CYP24 plays an essential role in the metabolism of ST-630 to yield its 23S-hydroxylated metabolite, as observed in cultured cells and experimental animal studies.
authors.affiliation: Biotechnology Laboratory, Sumitomo Chemical Co., Ltd, Hyogo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
authors.forename: M
authors.initials: M
authors.lastname: Akiyoshi-Shibata
authors.forename: T
authors.initials: T
authors.lastname: Sakaki
authors.forename: Y
authors.initials: Y
authors.lastname: Yabusaki
mesh_terms: D000325:Adrenodoxin / Q000378:metabolism; D000818:Animals; D001711:Biotransformation; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics; D002417:Cattle; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004926:Escherichia coli; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism; D006900:Hydroxylation; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000378:metabolism*; D013379:Substrate Specificity; D065668:Vitamin D3 24-Hydroxylase; D005466:Fluorocarbons
chemical_list: D000325:Adrenodoxin; D002117:Calcitriol; D003577:Cytochrome P-450 Enzyme System; D005287:Ferredoxin-NADP Reductase; D011994:Recombinant Proteins; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; C040488:26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3; D005466:Fluorocarbons