Functional characterization of two novel CYP2C19 variants (CYP2C19*18 and CYP2C19*19) found in a Japanese population.
Cytochrome P450 2C19 (CYP2C19) plays an important role in the metabolism of a wide range of therapeutic drugs and exhibits genetic polymorphism with interindividual differences in metabolic activity. We have previously described two CYP2C19 allelic variants, namely CYP2C19*18 and CYP2C19*19 with Arg329His/Ile331Val and Ser51Gly/Ile331Val substitutions, respectively. In order to investigate precisely the effect of amino acid substitutions on CYP2C19 function, CYP2C19 proteins of the wild-type (CYP2C19.1B having Ile331Val) and variants (CYP2C19.18 and CYP2C19.19) were heterologously expressed in yeast cells, and their S-mephenytoin 4'-hydroxylation activities were determined. The K(m) value of CYP2C19.19 for S-mephenytoin 4'-hydroxylation was significantly higher (3.0-fold) than that of CYP2C19.1B. Although no significant differences in V(max) values on the basis of microsomal and functional CYP protein levels were observed between CYP2C19.1B and CYP2C19.19, the V(max)/K(m) values of CYP2C19.19 were significantly reduced to 29-47% of CYP2C19.1B. By contrast, the K(m), V(max) or V(max)/K(m) values of CYP2C19.18 were similar to those of CYP2C19.1B. These results suggest that Ser51Gly substitution in CYP2C19.19 decreases the affinity toward S-mephenytoin of CYP2C19 enzyme, and imply that the genetic polymorphism of CYP2C19*19 also causes variations in the clinical response to drugs metabolized by CYP2C19.
Hanioka
N
N
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama, 700-8530, Japan.
Tsuneto
Y
Y
Saito
Y
Y
Sumada
T
T
Maekawa
K
K
Saito
K
K
Sawada
J
J
Narimatsu
S
S
D019943:Amino Acid Substitution; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D044466:Asian People; D065731:Cytochrome P-450 CYP2C19; D006801:Humans; D007564:Japan; D007700:Kinetics; D008617:Mephenytoin / Q000737:chemistry*; D006899:Mixed Function Oxygenases / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D020125:Mutation, Missense; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013379:Substrate Specificity / Q000235:genetics
D011994:Recombinant Proteins; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D008617:Mephenytoin