Catalytic activity of water molecules in gas‐phase glycine dimerization,International Journal of Quantum Chemistry

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Catalytic activity of water molecules in gas‐phase glycine dimerization
International Journal of Quantum Chemistry ( IF 2.3 ) Pub Date : 2020-09-12 , DOI: 10.1002/qua.26469
Ariel G. Gale ₁ , Tuguldur T. Odbadrakh ₁ , George C. Shields ₁

Affiliation

The dimerization of glycine is the simplest oligomerization of amino acids and plays an important role in biology. Although this reaction is thermodynamically unfavorable in the aqueous phase, it has been shown to be spontaneous in the gas phase and proceeds via two different concerted reaction mechanisms known as cis and trans. This may have profound implications in prebiotic chemistry as common atmospheric prenucleation clusters are thought to have participated in gas‐phase reactions in the early Earth's atmosphere. We hypothesize that particular arrangements of water molecules in these clusters could lead to lowering of the reaction barrier of amino acid dimerization and could lead to abiotic catalysis toward polypeptides. We test our hypothesis on a system of the cis transition state of glycine dimerization solvated by one to five water molecules using a combination of a genetic algorithm‐based configurational sampling, density functional theory geometries, and domain‐based local pair natural orbital coupled‐cluster electronic structure. First, we discuss the validity of the model chemistries used to obtain our results. Then, we show that the Gibbs free energy barrier for the concerted cis mechanism can indeed be lowered by the addition of up to five water molecules, depending on the temperature.

中文翻译：

水分子在气相甘氨酸二聚反应中的催化活性

甘氨酸的二聚是氨基酸最简单的低聚，在生物学中起重要作用。尽管该反应在水相中在热力学上是不利的，但已证明它在气相中是自发的，并通过两种不同的协同反应机理进行反应，即顺式和反式。这可能会对益生元化学产生深远的影响，因为通常的大气预核簇被认为参与了地球早期大气中的气相反应。我们假设在这些簇中水分子的特殊排列可能导致氨基酸二聚化反应障碍的降低，并可能导致对多肽的非生物催化。我们在顺式系统上检验我们的假设通过基于遗传算法的配置采样，密度泛函理论几何结构和基于域的局部对自然轨道耦合簇电子结构的组合，甘氨酸二聚化的过渡态被一到五个水分子溶剂化。首先，我们讨论用于获得结果的化学模型的有效性。然后，我们表明，根据温度，通过添加多达五个水分子，确实可以降低用于顺式顺式机理的吉布斯自由能垒。

更新日期：2020-09-23

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