Yedgar S, Tetreau C, Gavish B, Lavalette D
Inserm U350, Institut Curie, Orsay, France.
Biophys J. 1995 Feb;68(2):665-70. doi: 10.1016/S0006-3495(95)80227-4.
Laser photodissociation of respiratory proteins is followed by fast geminate recombination competing with escape of the oxygen molecule into the solvent. The escape rate from myoglobin or hemerythrin has been shown previously to exhibit a reciprocal power-law dependence on viscosity. We have reinvestigated oxygen escape from hemerythrin using a number of viscous cosolvents of varying molecular weight, from glycerol to dextrans up to 500 kDa. In isoviscous solutions, the strong viscosity dependence observed with small cosolvents is progressively reduced upon increasing the cosolvent's molecular weight and disappears at molecular weights greater than about 100 kDa. Thus, viscosity is not a suitable independent parameter to describe the data. The power of the viscosity dependence of the rate coefficient is shown here to be a function of the cosolvent's molecular weight, suggesting that local protein-solvent interactions rather than bulky viscosity are affecting protein dynamics.
呼吸蛋白的激光光解离之后是快速的双分子复合，该复合过程与氧分子逃逸到溶剂中相互竞争。先前已表明，肌红蛋白或蚯蚓血红蛋白的逃逸速率对粘度呈现倒数幂律依赖性。我们使用了多种分子量不同的粘性共溶剂，从甘油到分子量高达500 kDa的右旋糖酐，重新研究了蚯蚓血红蛋白中的氧逃逸情况。在等粘度溶液中，随着共溶剂分子量的增加，小共溶剂所观察到的强烈粘度依赖性逐渐降低，并在分子量大于约100 kDa时消失。因此，粘度不是描述这些数据的合适独立参数。此处表明，速率系数的粘度依赖性幂次是共溶剂分子量的函数，这表明局部蛋白质 - 溶剂相互作用而非大量的粘度在影响蛋白质动力学。
