Measurement of local viscosity of the hydration shell of protein by time-resolved fluorescence anisotropy spectroscopy

本研究通过测定荧光染料的旋转相关时间T_c来评价蛋白质表面水合区的局部粘度，发现该方法测得的T_c与溶剂粘度呈线性关系。基于连续激光的方法发现在F-肌动蛋白的肌动蛋白的374位连接的Cy3比在G-肌动蛋白附近连接的T_c更短，这与介电弛豫法的结果是一致的。另一方面，没有皮秒脉冲宽度的脉冲激光方法无法测量水中罗丹明6G等小荧光染料的T_c(？lt；1 ns)。

In this study, rotational correlation time Tc of fluorescent dye was measured to evaluate the local viscosity of the hydration region of protein surface.The Tc measured by this method was found to be in linear relation with the solvent viscosity. The CW-laser-based method revealed shorter Tc of Cy3 linked at Cys374 of actin in F-actin than around G-actin, which is consistent with the result by dielectric relaxation data.On the other hand,Tc (<1ns) of small fluorescent dye such as rhodamin 6G in water could not be measured by pulse-laser-based method without picosecond pulse width.We have designed a frequency-region fluorescent anisotropy spectroscopic method to measure Tc of small fluorescent dyes.