Pesce A, Capasso C, Battistoni A, Folcarelli S, Rotilio G, Desideri A, Bolognesi M
Dipartimento di Fisica and INFM, Universita' di Genova, Largo Rosanna Benzi, 10, 16132 Genova, Italy.
J Mol Biol. 1997 Dec 5;274(3):408-20. doi: 10.1006/jmbi.1997.1400.
The first three-dimensional structure of a functional monomeric Cu, Zn superoxide dismutase (from Escherichia coli, E_SOD) is reported at 2.0 A resolution (R-factor=16.8%). Compared to the homologous eukaryotic enzymes, E_SOD displays a perturbed antiparallel beta-barrel structure. The most striking structural features observed include extended amino acid insertions in the surface 1, 2-loop and S-S subloop, modification of the disulfide bridge connection, and loss of functional electrostatic residues, suggesting a modified control of substrate steering toward the catalytic center. The active site Cu2+ displays a distorted coordination sphere due to an unusually long bond to the metal-bridging residue His61. Inspection of the crystal packing does not show regions of extended contact indicative of a dimeric assembly. The molecular surface region involved in subunit dimerization in eukaryotic superoxide dismutases is structurally altered in E_SOD and displays a net polar nature.
报道了功能性单体铜锌超氧化物歧化酶（来自大肠杆菌，即E_SOD）在2.0埃分辨率下（R因子=16.8%）的首个三维结构。与同源的真核酶相比，E_SOD呈现出一种受干扰的反平行β桶结构。观察到的最显著结构特征包括表面1、2环和S-S亚环中的延伸氨基酸插入、二硫键连接的改变以及功能性静电残基的缺失，这表明对底物导向催化中心的控制有所改变。活性位点的Cu2+由于与金属桥连残基His61的键异常长而呈现出扭曲的配位球。对晶体堆积的检查未显示出表明二聚体组装的延伸接触区域。真核超氧化物歧化酶中参与亚基二聚化的分子表面区域在E_SOD中结构发生改变，并呈现出净极性性质。
