Molecular Dynamics Investigation of Clustering in Aqueous Glycine Solutions.
Molecular Dynamics Investigation of Clustering in Aqueous Glycine Solutions.
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甘氨酸水溶液中簇合物的分子动力学研究。
DOI：
10.1021/acs.jpcb.2c01975
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发表时间：
2022-06-30
影响因子：
3.3
通讯作者：
Sefcik, Jan
中科院分区：
文献类型：
--
作者：
Sweatman, Martin B.;Afify, Nasser D.;Ferreiro-Rangel, Carlos A.;Jorge, Miguel;Sefcik, Jan
最近的实验与不饱和的甘氨酸水溶液反复表现出巨大的液体状簇或直径约100 nm的纳米液滴的存在下。这些纳米液滴甚至在仔细努力去除和纯化甘氨酸溶液之后再次出现。这些簇的组成尚不清楚，尽管有人认为它们主要由甘氨酸（一种小而易溶的氨基酸）组成。为了深入了解这一现象，我们研究了甘氨酸在水溶液中的聚集浓度低于实验溶解度极限，在环境条件下使用大规模分子动力学模拟。采用基于1.14*CM1A部分电荷方案的分子力场模拟了甘氨酸的三种质子化状态（两性离子= GLZ，阴离子= GLA，阳离子= GLC），该方案结合了OPLS全原子力场和TIP3P水.当从分散态开始时，我们发现除非存在盐杂质，否则在我们的模拟中不会形成巨大的团簇。此外，如果从巨簇态开始模拟，我们发现它们倾向于在没有盐杂质的情况下溶解。因此，模拟结果几乎没有支持实验中看到的巨型团簇纯粹由甘氨酸（和水）组成的可能性。考虑到在实验中进行了艰苦的努力以除去杂质，例如作为盐，我们提出所观察到的巨大簇可能是由水性甘氨酸的反应产物的聚集引起的，例如二酮哌嗪或其他低聚甘氨酸，其可能难以使用常规方法与甘氨酸分离，或它们与甘氨酸的共聚集。
Recent experiments with undersaturated aqueous glycine solutions have repeatedly exhibited the presence of giant liquid-like clusters or nanodroplets around 100 nm in diameter. These nanodroplets re-appear even after careful efforts for their removal and purification of the glycine solution. The composition of these clusters is not clear, although it has been suggested that they are mainly composed of glycine, a small and very soluble amino acid. To gain insights into this phenomenon, we study the aggregation of glycine in aqueous solutions at concentrations below the experimental solubility limit using large-scale molecular dynamics simulations under ambient conditions. Three protonation states of glycine (zwitterion = GLZ, anion = GLA, and cation = GLC) are simulated using molecular force fields based on the 1.14*CM1A partial charge scheme, which incorporates the OPLS all-atom force field and TIP3P water. When initiated from dispersed states, we find that giant clusters do not form in our simulations unless salt impurities are present. Moreover, if simulations are initiated from giant cluster states, we find that they tend to dissolve in the absence of salt impurities. Therefore, the simulation results provide little support for the possibility that the giant clusters seen in experiments are composed purely of glycine (and water). Considering that strenuous efforts are made in experiments to remove impurities such as salt, we propose that the giant clusters observed might instead result from the aggregation of reaction products of aqueous glycine, such as diketopiperazine or other oligoglycines which may be difficult to separate from glycine using conventional methods, or their co-aggregation with glycine.
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影响因子：
14.9
作者：
Dodda LS;Cabeza de Vaca I;Tirado-Rives J;Jorgensen WL
通讯作者：
Jorgensen WL
影响因子：
3.8
作者：
Cheong, Daniel W.;Di Boon, Yi
通讯作者：
Di Boon, Yi
影响因子：
6
作者：
Di Gioacchino, Michael;Ricci, Maria Antonietta;Bruni, Fabio
通讯作者：
Bruni, Fabio
影响因子：
2.2
作者：
Elsila, Jamie E.;Glavin, Daniel P.;Dworkin, Jason P.
通讯作者：
Dworkin, Jason P.
影响因子：
2
作者：
Bujdák, J;Rode, BM
通讯作者：
Rode, BM