中文摘要：

虎纹捕鸟蛛毒素-IV（HWTX—IV）是从虎纹捕鸟蛛粗毒中分离纯化到的一种新型多肽类神经毒素，能明显抑制表达于大鼠背根神经节细胞的河豚毒素敏感型（TTX—S）钠通道．为了更好地研究该毒素的结构与功能之间的关系，采用芴甲氧羰基（Fmoc）固相多肽化学合成法合成了用谷氨酸（Glu）替代HWTX—IV第28位苏氨酸残基的突变体T28D-HWTX—IV，线性多肽合成产物经反相高效液相色谱（HPLC）分离纯化后进行谷胱甘肽氧化复性．复性产物采用基质辅助激光解析飞行时间质谱（MALDI—TOF／TOFMS）技术鉴定分子质量，通过全细胞膜片钳电生理技术测定其电压门控钠通道药理学活性,当第28位Thr残基被Glu取代后，突变体T28D—HWTX—IV对表达于大鼠DRG细胞膜上的TTX—S钠通道的IC50值约为362nmol／L，对TTX-S钠通道的抑制活性比天然HWTX—IV（IC50值=30nmol/L）下降了约12倍，显示第28位的Thr残基是HWTX—IV与TTX—S型钠通道相互作用的关键活性残基．目前的研究为进一步探索HWTX-IV的结构与功能关系及新型镇痛药物的研发奠定了基础．

英文摘要：

Huwentoxin-IV （HWTX-IV）, a novel neurotoxic polypeptide toxin characterized from Chinese tarantula Ornithoctonus huwena venom, which is found to inhibit tetrodotoxin-sensitive （TFX-S） sodium channels expressed in rat dorsal root ganglion （DRG） neurons. To investigate the structure-function relationship of the toxin, a mutant form of the HWTX-IV with Thr28 substituted by Glu was synthesized by solid-phase chemistry method with Fmoc-protected amino acids. The synthetic linear peptide was then purified by reversed-phase high performance liquid chromatography （RP-HPLC） and refolded with Glutathione oxidation. The relative molecular weight of the refolded product was analyzed by matrix-assisted laser resorption/ionization time-of-flight mass spectrometry. The prohibitive activity of sodium channels was analyzed by patchclamp electrophysiological experiment. Under the whole-cell patch-clamp configuration, the mutant T28D- HWTX-IV could inhibit the currents of the TTX-S sodium channel expressed on the cell membrane of rat dorsal root ganglion （DRG） neurons with IC50 value of 362 nmol/L. However, the prohibitive level of T28D-HWTX-IV on TFX-S sodium channels was reduced amino acid residue related to the interaction between by about 12 times, indicating that Thr28 was a key HWTX-IV and TI＇X-S sodium channels. The findings would facilitate further investigation of the structure-function relationship of HWTX-IV and developing drug candidate targeting TI＇X-S sodium channel in mammalian neurons.