Dynamical Effects of Trimethylamine N-Oxide on Aqueous Solutions of Urea.
Dynamical Effects of Trimethylamine N-Oxide on Aqueous Solutions of Urea.
复制标题
三甲胺 N-氧化物对尿素水溶液的动力学影响。
DOI：
10.1021/acs.jpcb.8b09874
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Ichiye,Toshiko
中科院分区：
文献类型：
--
作者：
Teng,Xiaojing;Ichiye,Toshiko
三甲基胺N-氧化物（TMAO）稳定蛋白质结构，而尿素使蛋白质不稳定，并且它们的相反作用可以在TMAO与尿素的1：2比例下被抵消。为了研究它们如何影响溶液动力学，分子动力学模拟已经进行了TMAO和尿素在不同浓度的水溶液。在二元溶液中，尿素主要减缓与其氢键合的沃茨的扩散（即，水化水）的扩散，而TMAO由于长寿命的TMAO-水氢键而显著地减缓了水化水和本体水两者的扩散。在三元溶液中，由于TMAO降低了本体水的扩散速率，不仅水-水氢键的寿命增加，而且尿素-水氢键的寿命也增加。此外，尿素和水之间短寿命氢键的不断形成和断裂似乎将能量赋予本体，而TMAO和水之间长寿命氢键减慢了本体，导致对三元溶液中本体水的补偿效应。这表明TMAO对尿素变性的抵消作用可能是使氢键与水形成更长的寿命，并抵消尿素对本体水的激发作用。
TrimethylamineN-oxide (TMAO) stabilizes protein structures, whereas urea destabilizes proteins, and their opposing effects can be counteracted at a 1:2 ratio of TMAO to urea. To investigate how they affect solution dynamics, molecular dynamics simulations have been carried out for aqueous solutions of TMAO and urea at different concentrations. In the binary solutions, urea mainly slows the diffusion of waters that are hydrogen bonded to it (i.e., hydration water), whereas TMAO dramatically slows the diffusion of both hydration water and bulk water because of long-lived TMAO-water hydrogen bonds. In the ternary solutions, because TMAO decreases the diffusion rate of bulk water, the lifetimes of not only water–water but also urea–water hydrogen bonds increase. In addition, the constant forming and breaking of short lifetime hydrogen bonds between urea and water appears to impart energy into the bulk, whereas the long lifetime hydrogen bonds between TMAO and water slows down the bulk, resulting in the compensating effects on bulk water in the ternary solution. This suggests that the counteracting effects of TMAO on urea denaturation may be both to make longer lived hydrogen bonds to water and to counter the energizing effects of urea on bulk water.