Interstellar Formation of Biorelevant Pyruvic Acid (CH3COCOOH)
Interstellar Formation of Biorelevant Pyruvic Acid (CH3COCOOH)
复制标题
DOI：
10.1016/j.chempr.2020.10.003
复制
发表时间：
2020-12-03
期刊：
影响因子：
23.5
通讯作者：
Kaiser, Ralf, I
中科院分区：
文献类型：
--
作者：
Kleimeier, N. Fabian;Eckhardt, Andre K.;Kaiser, Ralf, I
丙酮酸是益生化学中形成代谢物和氨基酸的关键分子。早期地球上没有液态水，内源性丙酮酸的形成是不可能的，而外源性输送构成了一个有吸引力的替代方案。然而，尽管在太空中检测到了200多个分子，丙酮酸仍然难以捉摸。在这里，我们描述了它是由乙醛(CH3CHO)和二氧化碳(CO2)中的羟基(HOCO中心点)和乙酰(CH3CO中心点)无障碍地复合而形成的，模拟了宇宙射线驱动的星际条件。利用同位素标记的ICE和光电离反射飞行时间质谱仪，反应产物在程序升温脱附阶段被选择性地光电离，并根据电离能区分异构体。这揭示了通过星际冷分子云和恒星形成区的非平衡反应合成丙酮酸的关键反应路径，从而为深空非生物有机合成提供了一个独特的切入点。
Pyruvic acid represents a key molecule in prebiotic chemistry to form metabolites and amino acids. Without liquid water on the early Earth, endogenous formation of pyruvic acid is unlikely, and an exogenous delivery constitutes an appealing alternative. However, despite the detection of more than 200 molecules in space, pyruvic acid is elusive. Here, we describe its formation by barrierless recombination of hydroxycarbonyl (HOCO center dot) and acetyl (CH3CO center dot) radicals in ices of acetaldehyde (CH3CHO) and carbon dioxide (CO2) modeling interstellar conditions driven by cosmic rays. Exploiting isotopically labeled ices and photoionization reflectron time-of-flight mass spectrometry, the reaction products were selectively photoionized in the temperature-programmed desorption phase and isomers discriminated based on their ionization energies. This reveals a key reaction pathway for pyruvic acid synthesis through non-equilibrium reactions in interstellar cold molecular clouds and star-forming regions, thus offering a unique entry point to abiotic organic synthesis in deep space.