Changes in the Enzymatic Properties of CYP2D6 by the Substitution of Phenylalanine at Position 120 by Alanine

Kazufumi Masuda, Hiroki Hashimoto, Keietsu Tamagake, Yukie Okuda, Daisuke Tsuzuki, Takashi Isobe, Hiroyuki Hichiya, Nobumitsu Hanioka, Shigeo Yamamoto, Shizuo Narimatsu
2004 Journal of health science  
The functional roles of phenylalanine at position 120 (Phe-120) in the oxidation of bunitrolol (BTL), debrisoquine (DB) and bufuralol (BF) by cytochrome P450 2D6 (CYP2D6) were examined using a yeast cell expression system (Saccharomyces cerevisiae AH-22 strain). The substitution of Phe-120 by alanine markedly increased the activities of enantiomeric BTL 4-hydroxylase and DB 4-hydroxylase, whereas it did not remarkably affect BF 1′′-hydroxylase activities. Kinetic studies revealed that the
more » ... aled that the substitution of Phe-120 by alanine increased the Km and Vmax values for enantiomeric BTL 4-hydroxylation, but increased only the Vmax value for DB 4-hydroxylation without changing the Km value. Km and Vmax values for BF 1′′-hydroxylation were similar between the mutant and the wild-type. The dissociation constants of the mutant calculated from the binding spectra for BTL enantiomers were higher than those of the wild-type, suggesting that the substitution of Phe-120 by alanine decreased the affinity of CYP2D6 for BTL enantiomers. These results indicate that Phe-120 has an important role in the oxidation of substrates by CYP2D6.
doi:10.1248/jhs.50.503 fatcat:iyzcmakwtjcmzky5jjsdi63u3u