Thomas P E, Reik L M, Ryan D E, Levin W
J Biol Chem. 1981 Jan 25;256(2):1044-52.
A procedure for the preparation of monospecific antibody directed against rat liver microsomal cytochrome P-45-a is described. This antibody, together with monospecific antibodies to cytochromes P-450b and P-450c, has been used to show that these three forms of cytochrome P-450 are distinct and share no common antigenic determinants. These antibodies (a) give single immunoprecipitin bands with detergent-solubilized microsomes; (b) do not cross-react with the purified heterologous antigens in Ouchterlony double diffusion analyses; (c) have no effect on catalytic activity of the heterologous antigens but completely inhibit the enzymatic activity of the homologous antigens; and (d) remove only the homologous antigen from detergent-solubilized microsomes when covalently bound to a solid support. With radial immunodiffusion assay, we have quantitated these three forms of cytochrome P-450 in liver microsomes after treatment of rats with seven different inducers of cytochrome P-450. The levels of these cytochrome P-450 isozymes vary independently and are also regulated by the age and sex of the animal. The antibodies have also been used to assess the contribution of cytochromes P-450a, P-450b, and P-450c in the metabolism of xenobiotics by rat liver microsomes. A large proportion of benzo(a)pyrene metabolism and testosterone 16 alpha-hydroxylation in microsomes from untreated rats is not catalyzed by cytochromes P-450a, P-450b, and P-450c. Epoxide hydrolase, another microsomal enzyme involved in the metabolism of xenobiotics, was also quantitated by radial immunodiffusion after prior treatment of rats with microsomal enzyme inducers. The inductions of epoxide hydrolase varies independently of the induction of cytochromes P-450a, P-450b, and P-450c.
本文描述了一种制备针对大鼠肝脏微粒体细胞色素P - 45 - a的单特异性抗体的方法。该抗体与细胞色素P - 450b和P - 450c的单特异性抗体一起，已被用于证明细胞色素P - 450的这三种形式是不同的，且没有共同的抗原决定簇。这些抗体：(a) 与去污剂溶解的微粒体产生单一免疫沉淀带；(b) 在双向免疫扩散分析中不与纯化的异源抗原发生交叉反应；(c) 对异源抗原的催化活性没有影响，但能完全抑制同源抗原的酶活性；(d) 当共价结合到固相支持物上时，仅从去污剂溶解的微粒体中去除同源抗原。通过放射免疫扩散测定法，我们对用七种不同的细胞色素P - 450诱导剂处理大鼠后的肝脏微粒体中这三种形式的细胞色素P - 450进行了定量。这些细胞色素P - 450同工酶的水平独立变化，并且也受动物年龄和性别的调节。这些抗体还被用于评估细胞色素P - 450a、P - 450b和P - 450c在大鼠肝脏微粒体对外源化合物代谢中的作用。未处理大鼠微粒体中很大一部分苯并(a)芘代谢和睾酮16α - 羟基化不是由细胞色素P - 450a、P - 450b和P - 450c催化的。环氧水解酶是另一种参与外源化合物代谢的微粒体酶，在用微粒体酶诱导剂预先处理大鼠后，也通过放射免疫扩散进行了定量。环氧水解酶的诱导与细胞色素P - 450a、P - 450b和P - 450c的诱导独立变化。
