【作者】 宗小红； 周平； 陈士明；

【Author】 Xiaohong Zong~a Ping Zhou~(a*) Shiming Chen~b ~a Key Laboratory of Molecular Engineering of Polymers,Ministry of Education,Macromolecular Science Department,Fudan University,220 Han Dan Road,Shanghai 200433,P.R.China ~b Analysis Measurement Center of Fudan University,Shanghai 200433

【机构】 复旦大学聚合物分子工程教育部重点实验室复旦大学高分子科学系； 复旦大学分析测试中心；

【摘要】 <正>蚕丝由于其出色的力学行为(高模量、高弹性),而引起人们对蚕丝蛋白基础及应用研究的广泛关注。蚕丝优异力学性能的产生与蚕丝蛋白的一级序列结构及其在吐丝过程中导致的二级结构的变化是分不开的。在蚕的丝腺体中,丝蛋白的构像为 silk Ⅰ,主要由无规线团组成。而在吐出的纤维状的丝中,丝蛋白的构像为 silk Ⅱ,主要是β折叠结构。我们在对金属离更多还原

【Abstract】 People have been interested in the silk protein,such as Bombyx mori,for its exceptional mechanical properties （high module as well as high elasticity）.The mechanical properties of silk protein are closely connected with the primary sequence of Bombyx mori silk and the change of secondary structure in the silk spinning process.Primarily,it has been accepted that there are two types of secondary structure,one is silk Ⅰ dominated by random coil conformation in the gland of silkworm,the other is silk Ⅱ dominated by β sheet conformation in silk.fiber.We have performed ¹³C CP-MAS solid state NMR of Bombyx mori silk protein to investigate the effect of metal ions on the conformation change of the silk fibroin protein.The NMR spectrum demonstrated that silk fibroin is dominantly of silk Ⅰ,whereas the fibroin with metal ion (Cu²⁺,Zn²⁺) additions has more silk Ⅱ conformation.Raman spectroscope shows the consistent results with that of NMR spectroscopy.The divalent copper ion has an electron orbital of d⁹ with an unpaired electron and is sensitive to EPR （electron paramagnetic resonance） signal for different binding mode.Therefore we hereby attempt to study the effect of copper （Ⅱ） ion on the conformation transition of silk fibroin protein,that is,to conceru the different binding mode of copper （Ⅱ）-silk fibroin complexes by EPR spectroscopy. Previous research indicated that there are different pH values for the silk gland in the different section of silkworm,and a lower pH gland is present near the spinneret.To elucidate the specific mode and site of binding with copper （Ⅱ）,we have studied a series of copper （Ⅱ） complexes of silk fibroin protein at different pH solution and ion concentration by EPR （conventional x-band）.The EPR spectrum shows that the g values are obviously connected with the solution pH and copper （Ⅱ） concentration.We suppose that the copper （Ⅱ） ion coordinates with the histidine residue and its adjacent glycine and alanine residues.There are two active hydrogen atoms m the nitrogen of histidine residue,leading to the different binding mode of copper （Ⅱ）-silk fibrom complexes at different pH solution.The further experiments are still progressing.更多还原