The Function of B Cytochrome in Complex II (Succinate-Ubiquinone Oxidoreductase)

复合物II（琥珀酸-泛醌氧化还原酶）是真核细胞和原核生物中TCA循环和线粒体有氧呼吸链的重要酶复合物。在这项研究中，我们对复合体II中的细胞色素b进行了如下描述。1)要解离配合物II的亚基，离子洗涤剂“萨科齐”是最有用的。2)在大肠杆菌细胞中建立了多质粒分离的sdh基因复合物II的体内重组体系。3)构建了蛔虫肌cDNA文库，免疫筛选了复合体II的细胞色素b亚基阳性克隆。4)从免疫筛选的cDNA中推导出人肝脏铁硫亚基的氨基酸序列。5)测定了蛔虫肌肉线粒体和纯化复合体II细胞色素的氧化还原电位，并与哺乳动物线粒体细胞色素的氧化还原电位进行了比较。蛔虫复合体II的细胞色素b_<558>的氧化还原电位高于牛心脏复合体II。

Complex II (succinate-ubiquinone oxidoreductase) is an important enzyme complex of both the TCA cycle and of the aerobic respiratory chain of mitochondria in eukaryotic cell and prokaryotic organisms. In this study, we have characterized the cytochrome b in complex II as described below.1) To dissociate the subunits of complex II, ionic detergent "sarkosyl" was most useful.2) In vivo reconstitution system of complex II from sdh genes separated in multiple plasmids in the Escherichia coli Cell has been established.3) cDNA library of Ascarismuscle has been constructed and positive clones for cytochorme b subunit of compleX II have been screened immunologically.4) Amino acid sequence of iron-sulfur subunit in human liver was deduced from cDNA which was isolated by immunoscreening.5) Oxidation-reduction potentials of cytochromes in muscle mitochondria of Ascaris and purified complex II were determined and compared with those in mammalian mitochondria. Oxidation-reduction potential of cytochrome b_<558> of Ascaris complex II was higher than that of bovine heart complex II.