Structure of an intermolecular electron-transfer complex: p-cresol methylhydroxylase at 6.0-A resolution.
Structure of an intermolecular electron-transfer complex: p-cresol methylhydroxylase at 6.0-A resolution.
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分子间电子转移复合物的结构：6.0-A 分辨率的对甲酚甲基羟化酶。
DOI：
10.1073/pnas.83.13.4626
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发表时间：
1986
影响因子：
11.1
通讯作者：
Hopper,DJ
中科院分区：
文献类型：
--
作者：
Shamala,N;Lim,LW;Mathews,FS;McIntire,W;Singer,TP;Hopper,DJ
对甲酚甲基羟化酶[4-甲酚：（受体）氧化还原酶（甲基-羟化），EC 1.17.99.1]是一种黄细胞色素c，其结构已在6.0-A分辨率下测定。结构分析是基于两个重原子衍生物的异常散射和2倍平均约非晶轴。该分子是α 2 β 2四聚体，细胞色素亚基的Mr约为8500，黄素蛋白亚基的Mr约为49，000。黄素蛋白亚基围绕分子2-折叠轴紧密堆积，而细胞色素亚基位于分子的外侧，每个亚基位于黄素蛋白亚基表面的凹陷中。这项研究的结果导致了以下结论。该酶的α 2 β 2四级结构与最初认为的α β不同。细胞色素亚基的方向和细胞色素和黄素蛋白亚基的表面互补性被清楚地定义。细胞色素亚基的大小与其他小细菌的细胞色素相似，但可能形成一个独特的亚类。酶的滴定（底物）行为和其他动力学性质是合理的四级结构。
The structure of p-cresol methylhydroxylase [4-cresol:(acceptor) oxidoreductase (methyl-hydroxylating), EC 1.17.99.1], a flavocytochrome c, has been determined at 6.0-A resolution. The structure analysis is based on two heavy-atom derivatives with anomalous scattering and 2-fold averaging about a noncrystallographic axis. The molecule is an alpha 2 beta 2 tetramer with a cytochrome subunit of Mr approximately 8500 and a flavoprotein subunit of Mr approximately 49,000. The flavoprotein subunits are tightly packed about the molecular 2-fold axis, whereas the cytochrome subunits are located on the outside of the molecule, each in a depression on the surface of a flavoprotein subunit. The results of this study have led to the following conclusions. The alpha 2 beta 2 quaternary structure of the enzyme is different from alpha beta as originally thought. The orientation of the cytochrome subunit and the surface complementarity of the cytochrome and flavoprotein subunits are clearly defined. The cytochrome subunit is similar in size to other small bacterial cytochromes but probably forms a distinct subclass. The titration (by substrate) behavior of the enzyme and other kinetic properties are rationalized by its quaternary structure.