Structure of variant-3 scorpion neurotoxin from Centruroides sculpturatus Ewing, refined at 1.8 A resolution.
Structure of variant-3 scorpion neurotoxin from Centruroides sculpturatus Ewing, refined at 1.8 A resolution.
复制标题
来自 Centruroides sculpturatus Ewing 的变体 3 蝎子神经毒素的结构，以 1.8 A 分辨率精制。
DOI：
10.1016/s0022-2836(83)80159-4
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发表时间：
1983
影响因子：
5.6
通讯作者：
Bugg,CE
中科院分区：
文献类型：
--
作者：
Almassy,RJ;Fontecilla-Camps,JC;Suddath,FL;Bugg,CE
本文用X射线衍射方法测定了雕纹蝎（Centruroides sculpturatusEwing）神经毒素变异蛋白-3（variant-3）的三维结构。65个残基的蛋白质的初始模型是通过多个同晶置换方法在3 μ m分辨率下获得的。通过限制差分傅立叶方法和自由原子块对角最小二乘法，在1·8 μ m分辨率下对结构进行了精细化。考虑到d = 1·8−7 σ且F0> 2·5σ（F0）的4900个反射，约束模型的最终R指数为0·16，自由原子模型的最终R指数为0·14。原子坐标的平均估计误差约为0.1 μ m。精细结构包括492个蛋白质原子;一个2-甲基-2，4-戊二醇分子，它紧密结合在蛋白质表面的疏水口袋中;和72个额外的溶剂位点。主要的二级结构特征是两个半圈的α-螺旋和一个反平行β-折叠的三链伸展。螺旋通过两个二硫键连接到β折叠的中间链，第三个二硫键位于附近。有几个环从这个致密的二级结构核心延伸出来。该蛋白质显示几个反向转角和一个高度受控的富含脯氨酸的COOH末端片段。其中一个脯氨酸残基（Pro 59）呈现酸式构象。该结构涉及44个分子内氢键。晶体学结果表明，在公布的一级结构中有两个主要的修正;其中一个已经被新的化学序列数据证实。该蛋白质显示出一个大的扁平表面，含有高浓度的疏水残基，沿着的大多数保守的氨基酸是在蝎子神经毒素中发现的。
The three-dimensional structure of the variant-3 protein neurotoxin from the scorpionCentruroides sculpturatusEwing has been determined by X-ray diffraction data. The initial model for the 65-residue protein was obtained at 3 Å resolution by multiple-isomorphous-replacement methods. The structure was refined at 1·8 Å resolution by restrained difference-Fourier methods, and by free-atom, block-diagonal least-squares. Considering the 4900 reflections for whichd= 1·8−7 Å andF0> 2·5σ(F0), the finalR-index is 0·16 for the restrained model, and 0·14 for the free-atom model. Average estimated errors in atomic co-ordinates are about 0·1 Å. The refined structure includes 492 protein atoms; one molecule of 2-methyl-2,4-pentanediol, which is tightly bound in a hydrophobic pocket on the surface of the protein; and 72 additional solvent sites. The major secondary structural features are two and a half turns of α-helix and a three-strand stretch of antiparallel β-sheet. The helix is connected to the middle strand of the β-sheet by two disulfide bridges, and a third disulfide bridge is located nearby. Several loops extend out of this dense core of secondary structure. The protein displays several reverse turns and a highly controted proline-rich, COOH-terminal segment. One of the proline residues (Pro59) assumes acis-conformation. The structure involves 44 intramolecular hydrogen bonds. The crystallographic results suggest two major corrections in the published primary structure; one of these has been confirmed by new chemical sequence data. The protein displays a large flattened surface that contains a high concentration of hydrophobic residues, along with most of the conserved amino acids that are found in the scorpion neurotoxins.