Inserm U779, University Paris 11, 94275 Le Kremlin-Bicêtre, France.
J Phys Chem B. 2011 Apr 14;115(14):3919-23. doi: 10.1021/jp107168b. Epub 2011 Mar 23.
Synchronized kinetics of ligand binding to a buried active site offers a look inside the protein. Photodissociated ligands are initially alongside their original binding site, so the recombination kinetics describes the trajectory for direct (geminate) rebinding or escape from the protein for the subsequent (bimolecular) rebinding phase. In the model case of myoglobin in water, most of the ligands escape; to better observe the geminate phase, high viscosity cosolvents were used: the kinetics were characterized by multiple barriers and a distribution of rates. An alternative method to enhance the fraction of geminate phase is the application of high pressure which closes the ligand migration channel; in this case of low viscosity without cosolvents, the geminate phase is closer to a simple exponential behavior. Samples with glycerol display the extended geminate kinetics, while samples in water under pressure do not.
配体与埋藏活性位点的同步结合动力学为我们深入了解蛋白质提供了可能。光解离的配体最初位于其原始结合部位附近，因此重组动力学描述了直接（成对）重新结合或从蛋白质中逃逸的轨迹，随后是后续的（双分子）重新结合阶段。在肌红蛋白溶于水的典型情况下，大多数配体都会逃逸；为了更好地观察成对阶段，使用了高粘度共溶剂：动力学的特征是存在多个障碍和速率分布。增强成对相分数的另一种方法是施加高压以关闭配体迁移通道；在这种低粘度且没有共溶剂的情况下，成对相更接近简单的指数行为。含有甘油的样品显示出扩展的成对动力学，而在高压下水溶液中的样品则没有。
