蜘蛛吐丝过程中钾的作用

用电感耦合等离子体质谱(ICP-MS)对蜘蛛Nephila丝腺体和丝进行测定,结果表明,钾在丝中的含量明显高于在丝腺体中的含量.同时,在蜘蛛丝蛋白溶液中加入氯化钾,溶液出现乳白色浑浊,表明有呈β-折叠构象的微纤产生.浊度测试发现,丝蛋白微纤会逐渐聚集成较大颗粒而在溶液中形成沉淀.另外,红外光谱和拉曼光谱亦证明钾能够使蜘蛛丝蛋白膜发生从无规线团/螺旋到β-折叠的构象转变.有理由认为钾在蜘蛛吐丝过程中起重要作用,它的存在有利于丝蛋白形成β-折叠结构.

Function of Potassium in Spinning Process of Spider Nephila

The spider dragline silks have attracted many interests for their marvelous comprehensive mechanical properties in the past few decades. However,the application of such an excellent material is extraordinarily restricted due to the difficulty of collection. Therefore,many attempts have been made in order to obtain spider silk fibers,in which the artificial spinning was thought to be most practical. Unfortunately,till now the properties of artificial silk fibers still cannot compare with the natural one. We think the reason for poor artificial silk fibers may be the only consideration of pure silk protein spinning solution and industrial spinning condition in the artificial spinning process. We know the spider spinning process in a bioprocess,therefore we think it is necessary to consider its biological environment. In this article,we found the potassium content was much higher in Nephila dragline silk than in its spinning dope by means of ICP-MS. We also found the addition of KCl into Nephila spidroin solution made it become turbid. The electron microscope observation revealed the nanofibril formation in the solution and the turbidimetry showed the turbidity declined about 1 h later indicating the precipitation of spidroin aggregation from the solution. Moreover,the conformation transition from random coil/helical to β-sheet was monitored with FTIR and Raman spectroscopy when the Nephila spidroin membranes were immersed in KCl solution. In conclusion,all the experimental results suggest that potassium may have a special effect in the spinning process of spider Nephila.