Abstract：
Quantum mechanical calculations are used to explore the thermodynamics of possible prebiotic synthesis of the building blocks of nucleic acids. Different combinations of D-ribofuranose (Ribf) and N-(2-aminoethyl)-glycine (AEG) (trifunctional connectors (TCs)); the nature of the Ribf, its anomeric form, and its ring puckering (conformation); and the nature of the nucleobases (recognition units (RUs)) are considered. The combinatorial explosion of possible nucleosides has been drastically reduced on physicochemical grounds followed by a detailed thermodynamic evaluation of alternative synthetic pathways. The synthesis of nucleosides containing N-(2-aminoethyl)-glycine (AEG) is predicted to be thermodynamically favored suggesting a possible role of AEG as a component of an ancestral proto-RNA that may have preceded today\'s nucleic acids. A new pathway for the building of free nucleotides (exemplified by 5\'-uridine monophosphate (UMP)) and of AEG dipeptides is proposed. This new pathway leads to a spontaneous formation of free UMP assisted by an AEG nucleoside in an aqueous environment. This appears to be a workaround to the \"water problem\" that prohibits the synthesis of nucleotides in water.
摘要：
量子力学计算用于探索核酸结构单元可能的益生元合成的热力学。D-呋喃核糖（Ribf）和N-（2-氨基乙基）-甘氨酸（AEG）（三官能连接器（TC））的不同组合；Ribf的性质，它的异头形式，及其环皱折（构象）；并考虑了核碱基（识别单元（RU））的性质。在物理化学基础上，可能的核苷的组合爆炸已大大减少，随后对替代合成途径进行了详细的热力学评估。预测含有N-（2-氨基乙基）-甘氨酸（AEG）的核苷的合成在热力学上是有利的，这表明AEG作为祖先原RNA的组成部分可能起作用，该成分可能先于当今的核酸。提出了构建游离核苷酸（以5'-尿苷一磷酸（UMP）为例）和AEG二肽的新途径。这种新的途径导致在水性环境中由AEG核苷辅助的游离UMP的自发形成。这似乎是“水问题”的解决方法，该问题禁止在水中合成核苷酸。
