Viscosity-dependent protein dynamics
Viscosity-dependent protein dynamics
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DOI：
10.1529/biophysj.106.093708
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发表时间：
2007-05-10
影响因子：
3.4
通讯作者：
Fayer, M. D.
中科院分区：
文献类型：
--
作者：
Finkelstein, Ilya J.;Massari, Aaron M.;Fayer, M. D.
光谱分辨的受激振动回波光谱是用来研究快速蛋白质动力学在室温下在四个血红素蛋白质：血红蛋白，肌红蛋白，肌红蛋白突变体与远端组氨酸取代缬氨酸（H64V），和细胞色素c552突变体与远端蛋氨酸取代丙氨酸（M61A）的散装溶液粘度的依赖性。添加果糖以使蛋白质水溶液的粘度增加许多数量级。四个球状蛋白质的快速动力学被发现是敏感的溶液粘度和渐近接近的动力学行为，以前观察到在室温下的糖玻璃。粘弹松弛模型的上下文中，将蛋白质作为一个可变形的呼吸球的粘度依赖的蛋白质动力学进行了分析。粘弹性模型是在定性与实验数据一致，但没有捕捉足够的系统细节，提供一个定量描述的基础波动幅度和弛豫速率。为了准确测定小体积蛋白质溶液的粘度，建立了一种基于水泛频近红外光谱的校正方法。
Spectrally resolved stimulated vibrational echo spectroscopy is used to investigate the dependence of fast protein dynamics on bulk solution viscosity at room temperature in four heme proteins: hemoglobin, myoglobin, a myoglobin mutant with the distal histidine replaced by a valine (H64V), and a cytochrome c552 mutant with the distal methionine replaced by an alanine (M61A). Fructose is added to increase the viscosity of the aqueous protein solutions over many orders of magnitude. The fast dynamics of the four globular proteins were found to be sensitive to solution viscosity and asymptotically approached the dynamical behavior that was previously observed in room temperature sugar glasses. The viscosity-dependent protein dynamics are analyzed in the context of a viscoelastic relaxation model that treats the protein as a deformable breathing sphere. The viscoelastic model is in qualitative agreement with the experimental data but does not capture sufficient system detail to offer a quantitative description of the underlying fluctuation amplitudes and relaxation rates. A calibration method based on the near-infrared spectrum of water overtones was constructed to accurately determine the viscosity of small volumes of protein solutions.