摘要
经CM—Sephadex C 25,Sephadex G 50及CM—Sephadex C 50三步柱层析,从平颏海蛇(Lapemis hardwickii)毒腺提取物中分离出神经毒组份X—2—4(Fr.X—2—4)。经三种不同类型的电泳鉴定,Fr.X—2—4为单一组份,其分子量为8000,等电点为pH 8.45。小鸡颈二腹肌及电生理实验证明,此组份为突触后神经毒,放射性配基结合实验表明,该毒份抑制^(125)I标记的眼镜蛇神经毒素与胆碱受体结合,其IC_(50)为7.45 nmol/L。拉曼光谱提示该神经毒的二级结构主要是β折叠和无规卷曲。
Neurotoxin fraction X-2-4 was isolated from the venom of a Chinese sea snake,Lapemis hardwickli by CM-Sephadex C 25,CM-Sephadex G 50 and CM-Sephadex C 50 column chromatography.It appeared as a single band on the polyacryla-mide disc gel electrophoresis,SDS-PAGE andisoelectrofocusing electrophoresis.The molecular weight of fraction X-2-4 was to be 8 000 by SDS-PAGE.The pI is about 8.45.It consists of 67 or 69 amino acids.Its LD50 value was determined by injecting ip it(161μg/kg)into mice.The fraction X-2-4 was a postsynaptic neurotoxin by experiments on the chicken-biventer cervicis preparations.The amplitudes of EPPs and mEPPs of the frog sartorius muscles were depressed by it,but neither the frequency of mEPPs nor the resting membrane potential of the muscle fibers was affected.It inhibited the binding of [125I] cobrotoxin to the solubilized AChR from Narcine maculata and the IC50 was 7.45 nmol/L.The Raman data indicated that the peptide back-bone conformation of fraction X-2-4 was mainly β-sheet and random coil.The results suggest that the fraction X-2-4 is a new long chain of postsynaptic neurotoxin.
出处
《中国药理学与毒理学杂志》
CAS
CSCD
北大核心
1990年第2期120-126,共7页
Chinese Journal of Pharmacology and Toxicology
关键词
平ke海蛇
神经毒素
药理
Lapemis hardwickii
neurotoxin
end-plate potential
minute end-plate potential
Raman spectrum