title: Influence of CYP2C19*18 and CYP2C19*19 alleles on omeprazole 5-hydroxylation: in vitro functional analysis of recombinant enzymes expressed in Saccharomyces cerevisiae.
abstract: Omeprazole is one of the most widely used proton pump inhibitors for the treatment of gastric acid-related disorders. The major metabolic pathway of omeprazole is 5-hydroxylation, which is catalysed by CYP2C19. In this study, the effect of CYP2C19*18 and CYP2C19*19 alleles on omeprazole 5-hydroxylation was studied using recombinant CYP2C19 enzymes of wild-type (CYP2C19.1B having Ile331Val) and variants (CYP2C19.18 having Arg329His/Ile331Val and CYP2C19.19 Ser51Gly/Ile331Val) expressed in yeast cells. The K(m) value for omeprazole 5-hydroxylation of CYP2C19.1B was 1.46 microM. The K(m) value of CYP2C19.19 was significantly higher (1.5-fold) than that of CYP2C19.1B. V(max) and V(max)/K(m) values for omeprazole 5-hydroxylation of CYP2C19.1B on the basis of cytochrome P450 protein level were 8.09 pmol/min./pmol CYP and 5.45 microl/min./pmol CYP, respectively. The V(max) value of CYP2C19.19 was significantly higher (1.8-fold) than that of CYP2C19.1B, whereas the V(max)/K(m) value was comparable to that of CYP2C19.1B. In contrast, K(m), V(max) and V(max)/K(m) values of CYP2C19.18 were similar to those of CYP2C19.1B. These results suggest that CYP2C19*19 allele decreases the affinity between CYP2C19 enzyme and the substrate in omeprazole metabolism.
authors.affiliation: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Okayama, Japan.
authors.forename: Nobumitsu
authors.initials: N
authors.lastname: Hanioka
authors.forename: Yumi
authors.initials: Y
authors.lastname: Tsuneto
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Keiko
authors.initials: K
authors.lastname: Maekawa
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Sawada
authors.forename: Shizuo
authors.initials: S
authors.lastname: Narimatsu
mesh_terms: D000483:Alleles; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D065731:Cytochrome P-450 CYP2C19; D006801:Humans; D006900:Hydroxylation; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D009853:Omeprazole / Q000378:metabolism*; D011110:Polymorphism, Genetic; D054328:Proton Pump Inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D054328:Proton Pump Inhibitors; D011994:Recombinant Proteins; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole