STRUCTURE OF FERRICYTOCHROME C' FROM RHODOSPIRILLUM-MOLISCHIANUM AT 1.67-A RESOLUTION
STRUCTURE OF FERRICYTOCHROME C' FROM RHODOSPIRILLUM-MOLISCHIANUM AT 1.67-A RESOLUTION
复制标题
DOI：
10.1016/0022-2836(85)90135-4
复制
发表时间：
1985-12-05
影响因子：
5.6
通讯作者：
SALEMME, FR
中科院分区：
文献类型：
--
作者：
FINZEL, BC;WEBER, PC;SALEMME, FR
来自 Molischianum 红螺菌的铁细胞色素 c'' 的结构已通过晶体学精修至 1.67 .ANG。使用倒易空间和约束最小二乘细化方法的组合进行分辨率。使用 1 > .sigma 测量的 30.533 次反射的最终晶体学 R 因子。 (I) 无穷大和 1.67 .ANG 之间。是0.188。最终模型包含 1944 个独特的蛋白质原子（总共 1972 个）以及 194 个结合的溶剂分子。对该结构的详细构象特性、二级结构特征、温度因素行为、结合溶剂位点和血红素几何形状进行了分析。细胞色素c''晶体的不对称单元包含由化学上相同的128个残基的多肽链组成的二聚体。尽管精炼的结构显示单体非常相似，但对确实发生的差异的检查可以评估不同的晶格接触如何影响蛋白质构象和溶剂结合。特别是，比较两个亚基中的溶剂结合位点可以识别不被晶格相互作用改变的共同组。这些溶剂相互作用在不同晶格环境中的保留表明它们在溶液中的蛋白质稳定中发挥结构作用。精细的结构还揭示了一些与配体结合特性和细胞色素 c'' 不寻常的混合自旋态特征相关的新特征。最后，对细胞色素 c'' 和其他结构上不相关的 c 型细胞色素中血红素结合几何形状的比较表明，在所检查的七个示例中存在两种替代的但空间有利的构象变体。
The structure of ferricytochrome c'' from Rhodospirillum molischianum has been crystallographically refined to 1.67 .ANG. resolution using a combination of reciprocal space and restrained least-squares refinement methods. The final crystallographic R-factor for 30.533 reflections measured with 1 > .sigma. (I) between infinity and 1.67 .ANG. is 0.188. The final model incorporates 1944 unique protein atoms (of a total of 1972) together with 194 bound solvent molecules. The structure has been analysed with respect to its detailed conformational properties, secondary structural features, temperature factor behavior, bound solvent sites, and heme geometry. The asymmetric unit of the cytochrome c'' crystal contains a dimer composed of chemically identical 128-residue polypeptide chains. Although the refined structure shows the monomers to be very similar, examination of the differences that do occur allows an evaluation of how different lattice contacts affect protein conformation and solvent binding. In particular, comparison of solvent binding sites in the two subunits allows identification of a common set that are not altered by lattice interactions. The preservation of these solvent interactions in different lattice environments suggests that they play a structural role in protein stabilization in solution. The refined structure additionally reveals some new features that relate to the ligand binding properties and unusual mixed-spin state character of cytochrome c''. Finally, comparison of the heme binding geometry in cytochrome c'' and other structurally unrelated c-type cytochromes shows that two alternative, but sterically favorable, conformational variants occur among the seven examples examined.