Crystal structure of Azotobacter cytochrome c5 at 2.5 A resolution.
Crystal structure of Azotobacter cytochrome c5 at 2.5 A resolution.
复制标题
固氮杆菌细胞色素 c5 的晶体结构，分辨率为 2.5 A。
DOI：
10.1016/0022-2836(85)90380-8
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发表时间：
1985
影响因子：
5.6
通讯作者：
Stout,CD
中科院分区：
文献类型：
--
作者：
Carter,DC;Melis,KA;O'Donnell,SE;Burgess,BK;FureyJr,WR;Wang,BC;Stout,CD
对棕色固氮菌细胞色素5的晶体结构进行了解析，并在2.5？分辨率下得到R值为0.29。用单斜晶型解析了氧化蛋白的结构。该结构通过多个同构取代基求解，重新拟合到溶剂水平的多个同构取代图，并用约束最小二乘法进行精化，结构显示单体在晶体结构的2-折轴附近通过“暴露的血红素边缘”的疏水接触而结合。该单体的总体构象与铜绿假单胞菌嗜铬假单胞菌551相似。然而，相对于常见的血红素构象，C5和C551在82个α-碳位置上平均相差6.8ó，C5的丙酸酯更容易暴露在溶剂中。在“二聚体”界面上，血红素-血红素接触的最短距离为6.3？(铁到铁16.4？)。C5和C551的比对表明，尽管序列不同，但这两种细胞色素的电荷分布非常相似。二硫化物堆积在N-端和C-端螺旋之间的酪氨酸上。
The crystal structure of cytochromec5fromAzotobacter vinelandiihas been solved and refined to anRvalue of 0.29 at 2.5 Å resolution. The structure of the oxidized protein was solved using a monoclinic crystal form. The structure was solved by multiple isomorphous replacements, re-fit to a solvent-leveled multiple isomorphous replacement map, and refined by restrained least squares.The structure reveals monomers associated about the crystallographic 2-fold axis by hydrophobic contacts at the “exposed heme edge”. The overall conformation for the monomer is similar to that ofPseudomonas aeruginosacytochromec551. However, relative to a common heme conformation,c5and c551differ by an average of 6.8 Å over 82 α-carbon positions and the propionates ofc5are much more exposed to solvent. The shortest heme-heme contact at the “dimer” interface is 6.3 Å (Fe to Fe 16.4 Å). Alignment ofc5andc551shows that the two cytochromes, in spite of sequence differences, have remarkably similar charge distributions. A disulfide stacks on a tyrosine between the N- and C-terminal helices.