Three-dimensional structure of the "long" neurotoxin from cobra venom.
Three-dimensional structure of the "long" neurotoxin from cobra venom.
复制标题
眼镜蛇毒液“长”神经毒素的三维结构。
DOI：
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发表时间：
1980
影响因子：
11.1
通讯作者：
A. Maelicke
中科院分区：
文献类型：
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作者：
M. Walkinshaw;W. Saenger;A. Maelicke
α-眼镜蛇毒素是中华眼镜蛇毒中的一种“长”神经毒素，其三维结构已被测定，分辨率为2.8-A。六角针状晶体的空间群为P6522，晶胞参数为a=b=74.59 A，c=42.89 A，每个不对称单位有一个分子。通过利用单位HgI2分子的反常散射来解决位相模糊问题，用与HgI2同象的单一导数确定相。多肽链折叠成三个主要的环，一个尾巴从球状的头部伸出。突出的长中央环(残基21-40)两侧各有两个较短的环(残基4-13和44-55)；尾部(残基63-71)挂在该环的后面。分子构象由长环头部的四个二硫键和长环末端的一个二硫键决定，由涉及该环的三链β-折叠片断决定，由稳定其他两个环的疏水相互作用决定。甲眼镜蛇毒素的结构与所描述的“短的”蛇毒毒素b的结构进行了比较，后者显示出相似的结构和功能不变基团的排列。
The three-dimensional structure of alpha-cobra-toxin, the "long" neurotoxin from the venom of Naja naja siamensis, has been determined at 2.8-A resolution. Crystals grown as hexagonal needles have space group P6522 with unit cell parameters a = b = 74.59 A, c = 42.89 A; one molecule per asymmetric unit. Phases were determined with a single isomorphous derivative with HgI2 by using the anomalous scattering of the single-site HgI2 molecule to resolve the phase ambiguity. The polypeptide chain folds into three major loops and one tail emerging from a globular head. The protruding long central loop (residues 21-40) is flanked on either side by two shorter loops (residues 4-13 and 44-55); the tail piece (residues 63-71) hangs behind this loop. The molecular conformation is determined by four disulfides in the head and one at the tip of the long loop, by a triple-stranded beta-pleated sheet involving this loop, and by hydrophobic interactions stabilizing the other two loops. The structure of alpha-cobratoxin is compared to that described for the "short" erabutoxin b which shows similar arrangement of structurally and functionally invariant groups.