Ohmori S, Kudo S, Nakasa H, Horie T, Kitada M
Division of Pharmacy, Chiba University Hospital, Faculty of Medicine, Japan.
Biol Pharm Bull. 1994 Dec;17(12):1584-8. doi: 10.1248/bpb.17.1584.
We isolated a form of cytochrome P450 (P450) from hepatic microsomes of untreated doguera baboons. The final preparation (referred to as P450 BLa) was apparently homogenous, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The estimated minimum molecular weight of P450 BLa was 50 kDa. The N-terminal amino acid sequence of P450 BLa (identified 10 residues) was identical with that of P450 3A8 purified from cynomolgus monkeys. This protein was cross-reactive with antibodies raised against P450 3A4 and P450 CMLc which were P450 3A enzymes purified from hepatic microsomes of humans and cynomolgus monkeys, respectively. P450 BLa was capable of catalyzing testosterone 6 beta-hydroxylation and zonisamide reduction. P450 BLa antibody inhibited the activity of testosterone 6 beta-hydroxylase, but not the activities of testosterone 16 alpha- and 16 beta-hydroxylases in liver microsomes of doguera baboons. From these lines of evidence we conclude that P450 BLa can be classified as part of the P450 3A subfamily and acts as a constitutive testosterone 6 beta-hydroxylase in hepatic microsomes of doguera baboons.
我们从未经处理的杜格拉狒狒的肝微粒体中分离出一种细胞色素P450（P450）形式。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳判断，最终制品（称为P450 BLa）显然是均一的。P450 BLa的估计最小分子量为50 kDa。P450 BLa的N端氨基酸序列（鉴定出10个残基）与从食蟹猴纯化得到的P450 3A8的序列相同。该蛋白与分别针对从人和食蟹猴肝微粒体纯化得到的P450 3A酶P450 3A4和P450 CMLc产生的抗体发生交叉反应。P450 BLa能够催化睾酮6β-羟基化和唑尼沙胺还原。P450 BLa抗体抑制杜格拉狒狒肝微粒体中睾酮6β-羟化酶的活性，但不抑制睾酮16α-和16β-羟化酶的活性。基于这些证据，我们得出结论，P450 BLa可归类为P450 3A亚家族的一部分，并在杜格拉狒狒的肝微粒体中作为组成型睾酮6β-羟化酶发挥作用。
