Finucane M D, Jardetzky O
Stanford Magnetic Resonance Laboratory, Stanford University, CA 94305-5055, USA.
J Mol Biol. 1995 Nov 3;253(4):576-89. doi: 10.1006/jmbi.1995.0574.
Amide proton exchange rates have been measured for fast-exchanging amides in trp aporepressor, and compared with the rates measured in the holorepressor. The results indicate that the presence of the ligand stabilizes all of the amide protons in the molecule against exchange, not just those whose access to solvent it directly hinders. This global hindering of the exchange process by tryptophan implies that there is a non-random element in the transmission mechanism, so that damping of the exchange in one part of the molecule also damps exchange in another region. This damping at a distance is not associated with any measurable changes in the intervening average secondary structure. This suggests the existence of a concerted dynamic process in the protein backbone that is modulated by ligand binding and in turn affects the observed backbone proton exchange.
已测量了色氨酸无辅基阻遏物中快速交换酰胺的酰胺质子交换速率，并与全阻遏物中测得的速率进行了比较。结果表明，配体的存在使分子中的所有酰胺质子对交换具有稳定性，而不仅仅是那些其与溶剂的接触直接受到阻碍的质子。色氨酸对交换过程的这种全局阻碍意味着在传递机制中存在一个非随机因素，因此分子一部分中交换的阻尼也会使另一区域的交换受到阻尼。这种远距离的阻尼与中间平均二级结构中任何可测量的变化无关。这表明在蛋白质主链中存在一个协同动态过程，该过程由配体结合调节，进而影响观察到的主链质子交换。
