Prebiotic thiol-catalyzed thioamide bond formation

Thioamide bonds are important intermediates in prebiotic chemistry. In cyanosul- fidic prebiotic chemistry, they serve as crucial intermediates in the pathways that lead to the formation of many important biomolecules (e.g., amino acids). They can also serve as purine and pyrimidine precursors, the two classes of het- erocycle employed in genetic molecules. Despite their importance, the formation of thioamide bonds from nitriles under prebiotic conditions has required large excesses of sulfide or compounds with unknown prebiotic sources. We describe here the thiol-catalyzed formation of thioamide bonds from nitriles. We show that the formation of the simplest of these compounds, thioformamide, forms readily in spark-discharge experiments from HCN and sulfide, suggesting poten- tial accumulation on early Earth. Lastly, we demonstrate that thioformamide has a Gibbs energy of hydrolysis (∆G◦r) comparable to other energy-currencies on early Earth such as pyrophosphate and thioester bonds. Overall, our findings imply that thioamides might have been abundant on early Earth and served a variety of functions during chemical evolution.硫酰胺键（thioamide bond）是前生物化学（prebiotic chemistry）中的关键中间体。在氰硫化物前生物化学（cyanosulfidic prebiotic chemistry）体系中，它们是诸多重要生物分子（例如氨基酸）合成通路的核心中间体；此外，硫酰胺键还可作为嘌呤（purine）与嘧啶（pyrimidine）的前体——这两类杂环化合物（heterocycle）是遗传分子中所采用的基础结构单元。尽管硫酰胺键的生物学意义显著，但在前生物条件下由腈类（nitriles）合成硫酰胺键，通常需要使用过量硫化物，或是采用来源不明的前生物相关化合物。本文报道了一种硫醇（thiol）催化下由腈类合成硫酰胺键的方法，研究发现其中最简单的硫酰胺类化合物——硫代甲酰胺（thioformamide），可在氰化氢（HCN）与硫化物参与的火花放电实验中顺利生成，这提示这类化合物有望在早期地球环境中大量积累。此外，本研究证实硫代甲酰胺的水解吉布斯自由能（∆G◦r）与早期地球其他高能载体（如焦磷酸（pyrophosphate）与硫酯键（thioester bond））相当。综上，本研究结果表明，硫酰胺类化合物可能曾广泛存在于早期地球，并在化学演化过程中发挥了多样的功能。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于前生物化学中硫代酰胺键的形成研究，通过实验展示了硫醇催化从腈类合成硫代酰胺键的机制，并探讨了硫代甲酰胺在早期地球的潜在积累及其能量特性，为理解化学进化提供了关键数据。