Frey T G
Department of Biology and Molecular Biology Institute, San Diego State University, California 92182.
Microsc Res Tech. 1994 Mar 1;27(4):319-32. doi: 10.1002/jemt.1070270407.
Cytochrome c oxidase is a complex integral membrane protein consisting of 13 different polypeptide chains and four metal centers having a total molecular weight of approximately 200,000 daltons. It can be isolated in two 2-dimensional crystalline forms differing in aggregation state of the enzyme. One crystal form consists of cytochrome oxidase dimers (approximately 400,000 daltons) embedded unidirectionally in the lipid bilayer of a collapsed vesicle while the other form consists of crystalline sheets of cytochrome oxidase monomers. Both crystal forms have been studied by electron microscopy during the past two decades, and this paper summarizes the results of early structural studies as well as more recent results applying techniques of cryoelectron microscopy and digital image processing. The structure of frozen-hydrated cytochrome oxidase dimers at 20 A resolution is discussed as well as the packing of monomers within dimers and the site of cytochrome c binding.
细胞色素c氧化酶是一种复杂的整合膜蛋白，由13条不同的多肽链和四个金属中心组成，总分子量约为200,000道尔顿。它可以以两种二维晶体形式分离，这两种形式在酶的聚集状态上有所不同。一种晶体形式由细胞色素氧化酶二聚体（约400,000道尔顿）单向嵌入塌陷囊泡的脂质双层中组成，而另一种形式由细胞色素氧化酶单体的晶体片组成。在过去二十年中，这两种晶体形式都通过电子显微镜进行了研究，本文总结了早期结构研究的结果以及应用冷冻电子显微镜和数字图像处理技术的最新结果。讨论了在20埃分辨率下冷冻水合细胞色素氧化酶二聚体的结构，以及二聚体内单体的堆积和细胞色素c结合位点。
