几种新的蝎毒神经毒素的纯化及它们某些性质和结构的初步研究

PRIMARY STUDIES OF PURIFICATION AND PARTIAL CHARACTERIZATION OF SEVERAL NEW NEUROTOXINS FROM EAST-ASIA SCORPION

经Sephadex G-50和Sp-Sephadex C-25两次柱层析,从山东马氏钳蝎(Buthus martensi Karsch)粗毒中分离纯化得到8种哺乳动物神经毒(BmK Ⅰ-Ⅷ)和一种甲壳动物神经毒(CT)。纯度鉴定表明它们在聚丙烯酰胺凝胶电泳和等电聚焦电泳时均呈现一条主带。除BmK Ⅳ外,其等电点在7.9—9.1之间,但BmK Ⅳ呈酸性,其等电点为5.3。SDS-PAGE测得它们的分子量为6000—8000。哺乳动物神经毒的氨基酸组成中Asp的含量较多,而不含Met,CT的氨基酸组成中Gly的含量高于Asp,且含Met,但缺乏Ile和Val。 Bmk Ⅲ和Bmk Ⅳ的N端部分序列比较,发现N端序列具有较强的保守性,15个残基中相同的残基占60％,各组份的CD谱显示它们的主链构象很相似,主要二级结构是β折迭,不含或含较少α-螺旋。

The venom from the East-Asia scorpion (Buthus maritensii Karsch) was isolated and purified by Sephadex G-50 and sp-Sephadex G-25 chromatography one after another. Different mammal neurotoxins BmK Ⅰ - Ⅶ and Crustacea neurotoxin were obtained. The results of electrophoresis and isoelcctric focusing on polyacrylamide gel showed that they arc homogeneous on the whole. Except the BmK Ⅳ, their isoelectric points arc range from 7.9 to 9.1. The pI of BmK Ⅳ is pH 5.3. The molecular weights determined by SDS PAGE are range between 6000 and 8000. The amino acid compositions showed that Bmk Ⅰ-Ⅷ have a higher content of Asp and 1/2 Cys and lack Met but CT has a higher content of Gly and lacks He and Val. The comparison of N-terminal partial sequences of 15 amino acid residuces between BmK Ⅳ and BmK Ⅲ showed the homology more than 60%. The far UV CD Spectrum of several neurotoxins indicate that a mixture of β-pleatad sheet and aperiodic structure is the main feature of the secondary structure of them.