Characterization of rat and human CYP2J enzymes as Vitamin D 25-hydroxylases.
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.
Aiba
Isamu
I
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
Yamasaki
Tomoaki
T
Shinki
Toshimasa
T
Izumi
Shunsuke
S
Yamamoto
Keiko
K
Yamada
Sachiko
S
Terato
Hiroaki
H
Ide
Hiroshi
H
Ohyama
Yoshihiko
Y
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
D017931:DNA Primers; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D053493:Cholestanetriol 26-Monooxygenase