Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture, Kobe University, Kobe, Hyogo, 657-8501, Japan.
Biopharm Drug Dispos. 2013 Mar;34(2):87-97. doi: 10.1002/bdd.1825. Epub 2012 Dec 4.
CYP 2A6 is a human enzyme that metabolizes many xenobiotics including coumarin, indole, nicotine and carcinogenic nitrosamines. The gene for CYP2A6 is polymorphic. There are few data available to clarify the relationship between P450 genetic variants and the metabolism of materials in food. The CYP 2A6 wild-type protein and 13 mutants (CYP2A6.1, CYP2A6.2, CYP2A6.5, CYP2A6.6, CYP2A6.7, CYP2A6.8, CYP2A6.11, CYP2A6.15, CYP2A6.16, CYP2A6.17, CYP2A6.18, CYP2A6.21, CYP2A6.23 and CYP2A6.25) were co-expressed with NADPH-cytochrome P450 reductase in E. coli. The hydroxylase activities toward 7-ethoxycoumarin, coumarin, safrole, flavanone and hydroxyflavanone were examined. Ten types of CYP2A6 variants except for CYP2A6.2, CYP2A6.5 and CYP2A6.6 showed Soret peaks (450 nm) typical of P450 in the reduced CO-difference spectra and had 7-ethoxycoumarin O-deethylase activities. CYP2A6.15 and CYP2A6.18 showed higher activities for safrole 1'-hydroxylation than CYP2A6.1. CYP2A6.25 and CYP2A6.7 had lower safrole 1'-hydroxylase activities. CYP2A6.7 had lower flavanone 6- and 2'-hydroxylase activities, whereas CYP2A6.25 had higher 6-hydroxylase activity and lower 2'-hydroxylase activity. Hydroxyflavanone was metabolized by CYP2A6.25, but was not metabolized by wild-type CYP2A6.1. These results indicate that CYP2A6.25 possessed new substrate specificity toward flavonoids.
CYP2A6 是一种人类酶，可代谢许多异源生物，包括香豆素、吲哚、尼古丁和致癌亚硝胺。CYP2A6 基因是多态性的。目前关于 P450 遗传变异与食物中物质代谢的关系，相关数据很少。CYP2A6 野生型蛋白和 13 种突变体（CYP2A6.1、CYP2A6.2、CYP2A6.5、CYP2A6.6、CYP2A6.7、CYP2A6.8、CYP2A6.11、CYP2A6.15、CYP2A6.16、CYP2A6.17、CYP2A6.18、CYP2A6.21、CYP2A6.23 和 CYP2A6.25）与 NADPH-细胞色素 P450 还原酶在大肠杆菌中共表达。检测了 7-乙氧基香豆素、香豆素、黄樟素、黄烷酮和羟基黄烷酮的羟化酶活性。除 CYP2A6.2、CYP2A6.5 和 CYP2A6.6 外的 10 种 CYP2A6 变体在还原 CO-差光谱中显示出 P450 的 Soret 峰（450nm），具有 7-乙氧基香豆素 O-脱乙基酶活性。CYP2A6.15 和 CYP2A6.18 对黄樟素 1'-羟化的活性高于 CYP2A6.1。CYP2A6.25 和 CYP2A6.7 的黄樟素 1'-羟化酶活性较低。CYP2A6.7 对黄烷酮 6-和 2'-羟化酶的活性较低，而 CYP2A6.25 对 6-羟化酶的活性较高，对 2'-羟化酶的活性较低。羟基黄烷酮可被 CYP2A6.25 代谢，但不能被野生型 CYP2A6.1 代谢。这些结果表明，CYP2A6.25 对黄酮类化合物具有新的底物特异性。
