Extended metal environments of cytochrome c oxidase structures.
Extended metal environments of cytochrome c oxidase structures.
复制标题
细胞色素c氧化酶结构的扩展金属环境。
DOI：
10.1021/bi981390t
复制
发表时间：
1998
期刊：
影响因子：
2.9
通讯作者：
Karlin,KD
中科院分区：
文献类型：
--
作者：
Karlin,S;Zhu,ZY;Karlin,KD
牛心小球藻（PDB代码1 occ）和土壤细菌Paracoccus spermificans（1ar 1）的细胞色素氧化酶结构的金属包括一个双铜中心（CuA）、镁、两个近端血红素、一个铜（CuB）原子和一个钙。线粒体结构还具有结合的远距离锌离子。金属网站的扩展环境进行了分析，强调残基的第二壳的极性，疏水性，二级结构，溶剂的可及性，和H-键合网络。CuAmetal环境中的显著差异涉及1 occ中的D-51 I，1ar 1中不存在。D-51 I似乎在质子泵送途径中起重要作用。我们的分析揭示了几个统计学上显著的残基簇，包括半胱氨酸-组氨酸-酪氨酸簇重叠的CuA-Mg复合物;一个组氨酸-酸性簇包围环境的Mg，两个血红素，和CuB;和蛋白质表面上的混合电荷簇，这可能有助于稳定四级结构和/或介导对接到细胞色素。这些团簇可能构成电子转移，O2扩散和H2O运动的可能途径。亚基I和II界面上的许多氢键关系沿着将该表面划分为质子泵送的潜在参与者。
The metals of the cytochromecoxidase structures of the bovine heart mitochondrion (PDB code 1occ) and of the soil bacteriumParacoccus denitrificans(1ar1) include a dicopper center (CuA), magnesium, two proximal hemes, a copper (CuB) atom, and a calcium. The mitochondrial structure also possesses a bound distant zinc ion. The extended environments of the metal sites are analyzed emphasizing residues of the second shell in terms of polarity, hydrophobicity, secondary structure, solvent accessibility, and H-bonding networks. A significant difference in the CuAmetal environments concerns D-51 I in 1occ, absent from 1ar1. The D-51 I appears to play an important role in the proton pumping pathway. Our analysis uncovers several statistically significant residue clusters, including a cysteine-histidine-tyrosine cluster overlapping the CuA−Mg complex; a histidine-acidic cluster enveloping the environment of Mg, the two hemes, and CuB; and on the protein surface a mixed charge cluster, which may help stabilize the quaternary structure and/or mediate docking to cytochromec. These clusters may constitute possible pathways for electron transfer, for O2diffusion, and for H2O movement. Many hydrogen bonding relations along the interface of subunits I and II demarcate this surface as a potential participant in proton pumping.