Leroy E, Mikou A, Yang Y, Guittet E
Laboratoire de Résonance Magnétique Nucléaire, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
J Biomol Struct Dyn. 1994 Aug;12(1):001-17.
The 3D solution structure of alpha-cobratoxin, a neurotoxin purified from the Naja naja siamensis snake venom, has been determined by Nuclear Magnetic Resonance spectroscopy, in conjunction with distance geometry and restrained molecular dynamics, at pH 7.5. A total of 490 distance restraints were obtained from NOE intensities and 25 phi dihedral angle restraints deduced from J-coupling data. The generated structures are well defined with root mean square deviations from a geometrical mean structure of 0.107 +/- 0.036 nm for the backbone atoms and 0.128 +/- 0.073 nm for the side-chain atoms (considering residues 1 to 66 minus 26 to 35). A comparison between the generated structures at pH 7.5 and the mean NMR solution structure at pH 3.2 revealed that the 3D structure of alpha-cobratoxin is more compact at neutral pH. This major difference is mainly due to the pH-dependent conformational variations of three residues His18, Thr44 and Thr59.
从眼镜蛇（Naja naja siamensis）蛇毒中纯化得到的神经毒素α-银环蛇毒素的三维溶液结构，已通过核磁共振光谱法，结合距离几何算法和受限分子动力学方法，在pH 7.5条件下测定。共从NOE强度获得490个距离约束，并从J耦合数据推导出25个φ二面角约束。生成的结构定义明确，主链原子相对于几何平均结构的均方根偏差为0.107±0.036 nm，侧链原子（考虑第1至66位残基减去第26至35位残基）为0.128±0.073 nm。pH 7.5条件下生成的结构与pH 3.2条件下的平均NMR溶液结构之间的比较表明，α-银环蛇毒素的三维结构在中性pH下更为紧凑。这一主要差异主要归因于三个残基His18、Thr44和Thr59的pH依赖性构象变化。
