Mori N, Ishizaki H, Tu A T
Department of Biochemistry, Colorado State University, Fort Collins 80523.
J Pharm Pharmacol. 1989 May;41(5):331-4. doi: 10.1111/j.2042-7158.1989.tb06466.x.
Pelamis platurus (yellow-bellied sea snake) venom contains several neurotoxins, the major toxin, which is most toxic, and two other isotoxins. The second most toxic neurotoxin (Pelamis toxin b) was isolated and characterized. It contains 60 amino acid residues with only one residue difference from the major toxin, Pelamis toxin a. The difference is at the tenth amino acid residue from the acid terminal. The isoelectric point of toxin b is 8.7. Raman spectroscopic examination of toxin b indicates that the toxin contains a considerable amount of antiparallel beta-structure, beta-turn, and random coil without alpha-helix as the amide I band appears at 1673 cm-1 and the amide III band at 1246 cm-1. Circular dichroic studies also indicate a typical beta-sheet structure. The Pelamis toxin b is a typical postsynaptic neurotoxin as it binds to the acetylcholine receptor competitively with a well known toxin, alpha-bungarotoxin. The LD50 of toxin b is 0.185 microgram g-1 in mice by intravenous injection, indicating high toxicity of a postsynaptic neurotoxin.
黄腹海蛇毒液含有多种神经毒素，其中主要毒素毒性最强，还有另外两种同毒素。第二种毒性最强的神经毒素（黄腹海蛇毒素b）已被分离并鉴定。它含有60个氨基酸残基，与主要毒素黄腹海蛇毒素a仅有一个残基差异。差异位于酸末端的第十个氨基酸残基处。毒素b的等电点为8.7。对毒素b的拉曼光谱检查表明，该毒素含有大量反平行β结构、β转角和无α螺旋的无规卷曲，因为酰胺I带出现在1673 cm-1，酰胺III带出现在1246 cm-1。圆二色性研究也表明存在典型的β折叠结构。黄腹海蛇毒素b是一种典型的突触后神经毒素，因为它能与一种著名的毒素α-银环蛇毒素竞争性结合乙酰胆碱受体。通过静脉注射，毒素b对小鼠的半数致死量为0.185微克/克，表明突触后神经毒素具有高毒性。
