title: Characterization of rat and human CYP2J enzymes as Vitamin D 25-hydroxylases.
abstract: vitamin D is 25-hydroxylated in the liver, before being activated by 1alpha-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 D3 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 D3 (turnover number, 0.087 min(-1)), vitamin D2 (0.16 min(-1)), and 1alpha-hydroxyvitamin D3 (2.2 min(-1)). Interestingly, human CYP2J2 hydroxylated vitamin D2, an exogenous vitamin D, at a higher rate than it did vitamin D3, an endogenous vitamin D, whereas, rat CYP2J3 hydroxylated vitamin D3 (1.4 min(-1)) more efficiently than vitamin D2 (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 D3 and D2.
authors.affiliation: Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Isamu
authors.initials: I
authors.lastname: Aiba
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Yamasaki
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Shinki
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Izumi
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Sachiko
authors.initials: S
authors.lastname: Yamada
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Terato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ide
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Ohyama
mesh_terms: D000818:Animals; D001483:Base Sequence; D053493:Cholestanetriol 26-Monooxygenase / Q000737:chemistry / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers; D006801:Humans; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D053493:Cholestanetriol 26-Monooxygenase