Cho Y S, Wang Q J, Krogmann D, Whitmarsh J
Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA.
Biochim Biophys Acta. 1999 Oct 6;1413(2):92-7. doi: 10.1016/s0005-2736(99)00124-8.
Cytochrome c(6) is a soluble heme protein that serves as a photosynthetic electron transport component in cyanobacteria and algae, carrying electrons from the cytochrome bf complex to photosystem I. The rapid accumulation of cytochrome c(6) sequence data from a wide range of species, combined with significant advances in determining high resolution three-dimensional structures, provides a powerful database for investigating the relationship between structure and function. The fact that the gene encoding cytochrome c(6) can be readily modified in a number of species adds to the usefulness of cytochrome c(6) as a tool for comparative analysis. Efforts to relate cytochrome c(6) sequence information to structure, and structural information to function depend on knowledge of the physical and thermodynamic properties of the cytochrome from different species. To this end we have determined the optical extinction coefficient, the oxidation/reduction midpoint potential, and the pH dependence of the midpoint potential of cytochrome c(6) isolated from three cyanobacteria, Arthrospira maxima, Microcystis aeruginosa, and Synechocystis 6803.
细胞色素c(6)是一种可溶性血红素蛋白,在蓝细菌和藻类中作为光合电子传递成分,将电子从细胞色素bf复合物传递到光系统I。来自广泛物种的细胞色素c(6)序列数据的快速积累,加上在确定高分辨率三维结构方面的重大进展,为研究结构与功能之间的关系提供了一个强大的数据库。编码细胞色素c(6)的基因在许多物种中可以很容易地被修饰,这一事实增加了细胞色素c(6)作为比较分析工具的有用性。将细胞色素c(6)序列信息与结构以及结构信息与功能联系起来的努力,取决于对来自不同物种的细胞色素的物理和热力学性质的了解。为此,我们测定了从三种蓝细菌极大节旋藻、铜绿微囊藻和聚球藻6803中分离出的细胞色素c(6)的光消光系数、氧化/还原中点电位以及中点电位的pH依赖性。