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兔肝单体重组和膜微粒体单加氧酶系统的比较研究。I. NADPH-细胞色素P450还原酶和细胞色素P450 LM2(2B4)单体的性质

Comparative study of monomeric reconstituted and membrane microsomal monooxygenase systems of the rabbit liver. I. Properties of NADPH-cytochrome P450 reductase and cytochrome P450 LM2 (2B4) monomers.

作者信息

Kanaeva I P, Dedinskii I R, Skotselyas E D, Krainev A G, Guleva I V, Sevryukova I F, Koen Y M, Kuznetsova G P, Bachmanova G I, Archakov A I

机构信息

Institute of Biological and Medical Chemistry, Russian Academy of Medical Sciences, Moscow.

出版信息

Arch Biochem Biophys. 1992 Nov 1;298(2):395-402. doi: 10.1016/0003-9861(92)90427-x.

Abstract

Oligomers and monomers of NADPH-cytochrome P450 reductase and cytochrome P450 LM2 (2B4) isolated from the liver microsomes of phenobarbital-treated rabbits were examined for physicochemical properties and catalytic activities. As measured using laser correlation spectroscopy the particle sizes of NADPH-cytochrome P450 reductase and cytochrome P450 LM2 oligomers were 14.8 +/- 1.7 and 19.2 +/- 1.4 nm, respectively. Twenty-four-hour incubation with Emulgen 913 at 4 degrees C at a molar ratio of 1:100 led to the monomerization of NADPH-cytochrome P450 reductase and cytochrome P450 LM2 oligomers, the particle sizes diminishing to 6.1 +/- 1.3 and 5.2 +/- 0.4 nm, respectively. The thermal stability of NADPH-cytochrome P450 reductase monomers was the same as that of oligomers, whereas cytochrome P450 LM2 monomers were less thermostable than oligomers and cytochrome P450 in microsomes. Similar to cytochrome P450 LM2 oligomers and the microsomal hemoprotein, cytochrome P450 LM2 monomers formed complexes with type I and II substrates, but with Kd values higher than those of microsomes and cytochrome P450 LM2 oligomers. Kinetic parameters (Vmax and Km) of H2O2- and cumene hydroperoxide-dependent oxidation of benzphetamine and aniline in the presence of cytochrome P450 LM2 oligomers, monomers, and microsomes were determined. Peroxidase activities of the oligomers and monomers were the same, but were lower than those of microsomes. Thus the substitution of protein-protein interactions in cytochrome P450 LM2 oligomers with protein-detergent interactions in the monomers did not influence the catalytic properties of the hemoprotein.

摘要

对从苯巴比妥处理过的兔子肝脏微粒体中分离出的NADPH - 细胞色素P450还原酶和细胞色素P450 LM2(2B4)的寡聚体和单体进行了物理化学性质和催化活性的检测。使用激光相关光谱法测量,NADPH - 细胞色素P450还原酶和细胞色素P450 LM2寡聚体的粒径分别为14.8±1.7和19.2±1.4纳米。在4℃下以1:100的摩尔比与乳化剂913孵育24小时导致NADPH - 细胞色素P450还原酶和细胞色素P450 LM2寡聚体单体化,粒径分别减小至6.1±1.3和5.2±0.4纳米。NADPH - 细胞色素P450还原酶单体的热稳定性与寡聚体相同,而细胞色素P450 LM2单体的热稳定性低于寡聚体和微粒体中的细胞色素P450。与细胞色素P450 LM2寡聚体和微粒体血红蛋白相似,细胞色素P450 LM2单体与I型和II型底物形成复合物,但解离常数(Kd)值高于微粒体和细胞色素P450 LM2寡聚体。测定了在细胞色素P450 LM2寡聚体、单体和微粒体存在下,苯丙胺和苯胺的H2O2和氢过氧化异丙苯依赖性氧化的动力学参数(Vmax和Km)。寡聚体和单体的过氧化物酶活性相同,但低于微粒体。因此,用单体中的蛋白质 - 去污剂相互作用取代细胞色素P450 LM2寡聚体中的蛋白质 - 蛋白质相互作用不会影响血红蛋白的催化特性。

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