摘要
为研究丝素蛋白在氯化钙溶液溶解过程中结构的阶段性变化特征,通过荧光光谱、紫外可见吸收光谱和拉曼光谱技术探讨了不同溶解时间下钙离子对丝素蛋白结构的影响情况。结果表明,在90℃左右,丝素蛋白与氯化钙溶液(Ca Cl2∶H2O=111∶180,质量比)作用0~30 min的时间段内,随着溶解时间的延长,钙离子逐渐渗透到丝素蛋白分子中,与丝氨酸(Ser)、酪氨酸(Tyr)侧链羟基进行配位而形成螯合物,丝素蛋白逐渐溶胀,分子结构变得松弛,埋藏在非结晶区内的色氨酸(Trp)和Tyr也逐渐暴露出来,分子构象由β-折叠向α-螺旋或无规线团转变。此外,外源性荧光探针(ANS)的结果表明,随着溶解时间的延长,丝素蛋白中的疏水性基团逐渐暴露于溶液中。电镜结果表明,丝素蛋白在氯化钙溶液的作用下逐渐由带状转变为片层状,最终呈球状结构。这些结果对调控丝素蛋白在氯化钙溶液中的溶解过程有着较为重要的现实意义。
In order to study the structural periodic variation characteristics of silk fibroin dissolved in calcium chloride,spectroscopic techniques （e.g.static fluorescence spectroscopy,UV-vis absorption spectroscopy and Raman spectroscopy） were used to monitor and investigate the conformational transition of silk fibroin in aqueous solutions under different dissolution time for the first time.It was shown that silk fibroin dissolved in calcium chloride（CaCl2 ∶ H2O =111 ∶ 180,mass ratio） at about 90 ℃.With the extension of dissolution time from 0 min to 30 min,calcium ions progressively penetrated into the silk fibroin molecules,and forming chelate complex with hydroxyl ligand of serine （Ser） and tyrosine（Tyr） side chain.In addition,silk fibroin began to swell,molecular structure also became gradually loose.At the same time,tryptophan（Trp） and Tyr buried in the area of noncrystalline also were gradually exposed,molecular conformation was also mainly shifted from β-sheet crystal to α-helix or random coil.It was also found that the aggregating of hydrophobic side chains was increased with increase of dissolution time via exogenous fluorescence probe of 8-anilino-1-naph-thalenesulfonic acid （ANS）.Experimental results obtained from the scanning electron microscope （SEM） confirmed that almost all of silk fibers were dissolved within 30 min,presenting globular structure.While previously,a certain amount of residual fibroin fibers existed with relatively loose zonal structure,then becoming layered structure.Therefore,the results obtained have a important practical significance for the time controlling of silk fibroin dissolution in calcium chloride solution.
出处
《分析测试学报》
CAS
CSCD
北大核心
2014年第12期1410-1415,共6页
Journal of Instrumental Analysis
基金
广西科学研究与技术开发计划项目(桂科能14122009-3-3
桂科转12125006-30)
国家科技型中小企业技术创新项目(14C26214502814)
国家自然科学基金项目(21466006)
关键词
丝素蛋白
构象转变
荧光光谱
紫外光谱
拉曼光谱
silk fibroin
conformation transition
fluorescence spectrum
ultraviolet-visible absorption
Raman spectroscopy
