切变速度和Ca~(2+)对再生丝素蛋白溶液构象转变的影响

采用偏光显微镜和拉曼光谱研究了切变速度和Ca2+对再生丝素蛋白水溶液构象转变的影响.结果表明:切变速度和Ca2+是影响再生丝素蛋白溶液性质的两个主要因素,对于同一再生溶液,切变速度增大,溶液中丝素蛋白分子沿切变方向的有序排列也随之增加,丝素溶液更容易从无规线团或α-螺旋向β-折叠转变,并且转变的程度随着剪切速度的增加而加强;透析溶液中Ca2+含量增加,则样品出现偏光现象的临界切变速度有所降低.拉曼光谱显示丝素蛋白分子构象由SilkⅠ向SilkⅡ转变.

Effects of Shear Rate and Ca2+ on Conformational Transition in Regenerated Silk Fibroin Solution

Polarized light microscopy and Raman spectroscopy were used to study the effects of shear rate and Ca²⁺ ions on the conformational transition of the aqueous solution of regenerated silk fibroin. The results showed that the shear rate and Ca²⁺ ions are really the two main influencing factors. For the same regenerated solution, the higher the shear rate, the more the silk fibroin molecules in orderly arrangement along shear rate in the solution. Then, the solution is easier to be transferred to β-pleating conformation from irregular coil or α-helix one, and such a transition is strengthened with increasing shear rate. After dialysis the Ca²⁺ ion concentration in the solution increases, and the critical shear rate with which the polarized light is visible decreases to a certain extent. And the Raman spectra revealed that the molecular conformation of the silk fibroin is transferred to Silk II from Silk I.