V. M. Gorbatov Federal Research Center for Food Systems, Talalikhina St., 26, Moscow 109316, Russia.
Department of Physics and Engineering Environmental Protection, Northern (Arctic) Federal University, Severnaya Dvina Emb. 17, Arkhangelsk 163001, Russia.
Int J Mol Sci. 2023 Aug 19;24(16):12971. doi: 10.3390/ijms241612971.
Trimethylglycine (glycine betaine, GB) is an important organic osmolyte that accumulates in various plant species in response to environmental stresses and has significant potential as a bioactive agent with low environmental impact. It is assumed that the hydration of GB is playing an important role in the protective mechanism. The hydration and aggregation properties of GB have not yet been studied in detail at the atomistic level. In this work, noncovalent interactions in the GB dimer and its complexes with water and crystalline monohydrate are studied. Depending on the object, periodic and non-periodic DFT calculations are used. Particular attention is paid to the metric parameters and enthalpies of intermolecular hydrogen bonds. The identification of noncovalent interactions is carried out by means of the Bader analysis of periodic or non-periodic electron density. The enthalpy of hydrogen bonds is estimated using the Rosenberg formula (PCCP 2 (2000) 2699). The specific proton donor properties of glycine betaine are due to its ability to form intermolecular C-H∙∙∙O bonds with the oxygen atom of a water molecule or the carboxylate group of a neighboring GB. The enthalpy of these bonds can be significantly greater than 10 kJ/mol. The water molecule that forms a hydrogen bond with the carboxylate group of GB also interacts with its CH groups through lone pairs of electrons. The C-H∙∙∙O bonds contribute up to 40% of the total entropy of the GB-water interaction, which is about 45 kJ/mol. The possibility of identifying C-H∙∙∙O bonds by the proton nuclear magnetic resonance method is discussed.
三甲基甘氨酸（甘氨酸甜菜碱，GB）是一种重要的有机渗透物，可在各种植物物种中积累以响应环境胁迫，并且具有作为具有低环境影响的生物活性剂的巨大潜力。据推测，GB 的水合作用在保护机制中起着重要作用。GB 的水合和聚集性质尚未在原子水平上进行详细研究。在这项工作中，研究了 GB 二聚体及其与水和结晶一水合物的复合物中的非共价相互作用。根据对象，使用周期性和非周期性 DFT 计算。特别注意分子间氢键的度量参数和焓。通过周期性或非周期性电子密度的 Bader 分析来识别非共价相互作用。氢键的焓使用罗森伯格公式（PCCP 2（2000）2699）估算。甘氨酸甜菜碱的特殊质子供体性质归因于其形成分子间 C-H∙∙∙O 键的能力，这些键与水分子的氧原子或相邻 GB 的羧基基团相互作用。这些键的焓可以大大超过 10 kJ/mol。与 GB 羧酸盐基团形成氢键的水分子还通过孤对电子与其 CH 基团相互作用。C-H∙∙∙O 键对 GB-水相互作用的总熵的贡献高达 40％，约为 45 kJ/mol。讨论了通过质子核磁共振方法识别 C-H∙∙∙O 键的可能性。
