Characterization of rat and human CYP2J enzymes as Vitamin D 25-hydroxylases

• Published in: Steroids 2006-10, Vol.71 (10), p.849-856
• Main Authors: Aiba, Isamu, Yamasaki, Tomoaki, Shinki, Toshimasa, Izumi, Shunsuke, Yamamoto, Keiko, Yamada, Sachiko, Terato, Hiroaki, Ide, Hiroshi, Ohyama, Yoshihiko
• Format: Article
• Language: English
• Subjects: 25-Hydroxylase; Animals; Base Sequence; Biological and medical sciences; Cholestanetriol 26-Monooxygenase - chemistry; Cholestanetriol 26-Monooxygenase - metabolism; CYP2J2; CYP2J3; Cytochrome P-450 Enzyme System - chemistry; Cytochrome P-450 Enzyme System - metabolism; DNA Primers; Fundamental and applied biological sciences. Psychology; Humans; Rats; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Vertebrates: endocrinology; vitamin D 2; vitamin D 3
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/j.steroids.2006.04.009

vitamin D is 25-hydroxylated in the liver, before being activated by 1α-hydroxylation in the kidney. Recently, the rat cytochrome P450 2J3 (CYP2J3) has been identified as a principal vitamin D 25-hydroxylase in the rat [Yamasaki T, Izumi S, Ide H, Ohyama Y. Identification of a novel rat microsomal vitamin D 3 25-hydroxylase. J Biol Chem 2004;279(22):22848–56]. In this study, we examine whether human CYP2J2 that exhibits 73% amino acid homology to rat CYP2J3 has similar catalytic properties. Recombinant human CYP2J2 was overexpressed in Escherichia coli, purified, and assayed for vitamin D 25-hydroxylation activity. We found significant 25-hydroxylation activity toward vitamin D 3 (turnover number, 0.087 min −1), vitamin D 2 (0.16 min −1), and 1α-hydroxyvitamin D 3 (2.2 min −1). Interestingly, human CYP2J2 hydroxylated vitamin D 2, an exogenous vitamin D, at a higher rate than it did vitamin D 3, an endogenous vitamin D, whereas, rat CYP2J3 hydroxylated vitamin D 3 (1.4 min −1) more efficiently than vitamin D 2 (0.86 min −1). Our study demonstrated that human CYP2J2 exhibits 25-hydroxylation activity as well as rat CYP2J3, although the activity of human CYP2J2 is weaker than rat CYP2J3. CYP2J2 and CYP2J3 exhibit distinct preferences toward vitamin D 3 and D 2.