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首页> 外文期刊>Biochemistry >SOLUTION STRUCTURE OF LSIII, A LONG NEUROTOXIN FROM THE VENOM OF LATICAUDA SEMIFASCIATA
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SOLUTION STRUCTURE OF LSIII, A LONG NEUROTOXIN FROM THE VENOM OF LATICAUDA SEMIFASCIATA

机译：半边天锦蛇毒中长神经毒素LSIII的溶液结构

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摘要

We report the sequence-specific proton assignments and solution structure of the long neurotoxin LSIII from the venom of Laticauda semifasciata determined by two- and three-dimensional H-1 NMR. Input for structure calculations consisted of 497 NOE-derived distance restraints and 45 dihedral angle restraints obtained from J couplings. A two-partide-per-residue representation of protein structure was used to generate 200 initial structures which were then subjected to all-atom refinement by simulated annealing. Twenty-three final structures consistent with the experimental restraints were obtained; the average atomic RMS difference between the individual structures and the mean structure was 0.82 Angstrom for the backbone heavy atoms and 1.3 Angstrom for all heavy atoms (residues 1-26, 37-60). The main elements of regular secondary structure are a three-stranded antiparallel beta-sheet and three finger-like loops protruding from a globular core, consistent with previously reported structures of long neurotoxins. The end of the prominent loop II, which is involved in binding to acetylcholine receptor, is disordered relative to the rest of the molecule. A novel finding of this study is that the loop has a well defined local structure; this and other observations suggest this region moves as a rigid body. We propose that this motion is a heretofore unrecognized general feature of long neurotoxins, with specific consequences for binding to the acetylcholine receptor.
机译：我们报告序列特质子分配和解决方案结构的长神经毒素LSIII从二维和三维H-1核磁共振确定的半壁筋蛇毒的毒液。用于结构计算的输入包括497个NOE衍生的距离约束和从J联轴器获得的45个二面角约束。蛋白质结构的每个残基的两部分表示法用于生成200个初始结构，然后通过模拟退火对其进行全原子精炼。得到了与实验约束相一致的二十三个最终结构;骨架的重原子在单个结构和平均结构之间的平均原子RMS差为0.82埃，所有重原子的平均原子RMS差为1.3埃（残基1-26、37-60）。规则二级结构的主要元素是三链反平行β-折叠和从球状核突出的三个手指状环，与先前报道的长神经毒素结构一致。涉及与乙酰胆碱受体结合的突出的环II的末端相对于该分子的其余部分而言是无序的。这项研究的一个新发现是，环路具有明确定义的局部结构。该观察结果和其他观察结果表明该区域作为刚体运动。我们提出，该运动是长神经毒素迄今无法识别的一般特征，具有与乙酰胆碱受体结合的特定后果。

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