Caffrey M, Simorre J P, Cusanovich M, Marion D
Institut de Biologie Structurale Jean-Pierre Ebel (CNRS-CEA), Grenoble, France.
FEBS Lett. 1995 Jul 24;368(3):519-22. doi: 10.1016/0014-5793(95)00692-3.
The cytochrome c' are paramagnetic heme proteins generally consisting of two identical 14 kDa subunits. The recent assignment of the 1H and 15N resonances of the Rhodobacter capsulatus ferricytochrome c' has allowed characterization of the dynamic properties by measurement of the heteronuclear NOE for each resolved amide group. The relative importance of fast local motion and paramagnetic effect on nuclear relaxation were distinguished by comparison of the measured heteronuclear NOE with that of the overall experimental average. We show that the average experimental value of -0.16 corresponds to the rigid body motion expected for a spherical complex of 28 kDa. Residues 3-5, 50-55 and 69-70 exhibit decreased heteronuclear NOE due to local motions on a fast time scale with respect to molecular tumbling. Based on the X-ray crystal structure of the homologous cytochrome c' from Chromatium vinosum, the mobile regions correspond to the N-terminus of helix-1 and 2 regions of nonregular secondary structure located between helices-2 and -3.
细胞色素c'是顺磁性血红素蛋白，通常由两个相同的14 kDa亚基组成。最近对荚膜红细菌高铁细胞色素c'的1H和15N共振进行了归属，从而能够通过测量每个解析酰胺基团的异核NOE来表征其动力学性质。通过将测量的异核NOE与整体实验平均值进行比较，区分了快速局部运动和顺磁效应在核弛豫中的相对重要性。我们表明，-0.16的平均实验值对应于28 kDa球形复合物预期的刚体运动。由于相对于分子翻滚而言在快速时间尺度上的局部运动，第3 - 5位、50 - 55位和69 - 70位残基的异核NOE降低。基于来自嗜硫小红卵菌的同源细胞色素c'的X射线晶体结构，可移动区域对应于螺旋-1的N端以及位于螺旋-2和-3之间的非规则二级结构的2个区域。
