Pan Jian-Yi, Yu Zhi-Qiang
Zhejiang Sci-Tech University, Hangzhou 310018, China.
Dongwuxue Yanjiu. 2010 Dec;31(6):570-4. doi: 10.3724/SP.J.1141.2010.06570.
Hainantoxin-II (HnTx-II), a novel neurotoxin, was isolated from the venom of the Chinese bird spider (Haplopelma hainanum) by cation exchange chromatography and reverse-phase HPLC. The toxin was a single chain polypeptide with calculated molecular weight of 4 253.135 obtained by mass spectrometry. The complete amino acid sequence of HnTx-II was determined by Edman degradation and found to contain 37 residues with three disulfide bonds. Results showed HnTx-II can reversibly paralyze cockroaches for several hours after intra-abdominal injection with ED50 of 16 ug/g and kill the insects immediately at a dose of 60 ug/g. It was also shown to kill mice at a LD50 value of 1.41ug/g after intracerebroventricular injection. Hainantoxin-II shares 91% sequence homology with Huwentoxin-II (HwTx-II), an insecticidal peptide from another bird spider (Haplopelma schmidti) with a unique scaffold. While HnTx-II and HwTx-II both exhibit toxic activities in insects and mammals, HnTx-II shows higher insecticidal activity and lower lethiferous activity of mammals than HwTx-II. These results help clarify structural-functional relationships of the polypeptide toxin.
海南毒素-II（HnTx-II）是一种新型神经毒素，通过阳离子交换色谱法和反相高效液相色谱法从中国鸟蛛（海南捕鸟蛛）的毒液中分离得到。该毒素为单链多肽，经质谱测定其计算分子量为4253.135。通过埃德曼降解法测定了HnTx-II的完整氨基酸序列，发现其含有37个残基和三个二硫键。结果表明，腹腔注射后，HnTx-II能使蟑螂可逆性麻痹数小时，半数有效剂量（ED50）为16微克/克，剂量为60微克/克时可立即杀死昆虫。脑室内注射后，HnTx-II对小鼠的半数致死剂量（LD50）为1.41微克/克。海南毒素-II与虎纹毒素-II（HwTx-II）的序列同源性为91%，HwTx-II是另一种具有独特支架结构的鸟蛛（史氏捕鸟蛛）产生的杀虫肽。虽然HnTx-II和HwTx-II在昆虫和哺乳动物中均表现出毒性活性，但与HwTx-II相比，HnTx-II对昆虫的杀虫活性更高，对哺乳动物的致死活性更低。这些结果有助于阐明多肽毒素的结构-功能关系。
