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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Deprotonated Purine Dissociation: Experiments, Computations, and Astrobiological Implications
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Deprotonated Purine Dissociation: Experiments, Computations, and Astrobiological Implications

机译：去质子化的嘌呤解离：实验，计算和天文生物学的影响。

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A central focus of astrobiology is the determination of abiotic formation routes to important biomolecules. The dissociation mechanisms of these molecules lend valuable insights into their synthesis pathways. Because of the detection of organic anions in the interstellar medium (ISM), it is imperative to study their role in these syntheses. This work aims to experimentally and computationally examine deprotonated adenine and guanine dissociation in an effort to illuminate potential anionic precursors to purine formation. Collision-induced dissociation (CID) products and their branching fractions are experimentally measured using an ion trap mass spectrometer. Deprotonated guanine dissociates primarily by deammoniation (97%) with minor losses of carbodiimide (HNCNH) and/or cyanamide (NH2CN), and isocyanic acid (HNCO). Deprotonated adenine fragments by loss of hydrogen cyanide and/or isocyanide (HCN/HNC; 90%) and carbodiimide (HNCNH) and/or cyanamide (NH2CN; 10%). Tandem mass spectrometry (MS '') experiments reveal that deprotonated guanine fragments lose additional HCN and CO, while deprotonated adenine fragments successively lose HNC and HCN. Every neutral fragment observed in this study has been detected in the ISM, highlighting the potential for nucleobases such as these to form in such environments. Lastly, the acidity of abundant fragment ions is experimentally bracketed. Theoretical calculations at the B3LYP/6-311++G(d,p) level of theory are performed to delineate the mechanisms of dissociation and analyze the energies of reactants, intermediates, transition states, and products of these CID processes.
机译：占星生物学的重点是确定重要生物分子的非生物形成途径。这些分子的解离机制为其合成途径提供了宝贵的见识。由于在星际介质（ISM）中检测到有机阴离子，因此有必要研究它们在这些合成中的作用。这项工作旨在实验和计算上检查去质子化的腺嘌呤和鸟嘌呤的解离，以阐明可能形成嘌呤的阴离子前体。碰撞诱导解离（CID）产物及其分支分数是使用离子阱质谱仪通过实验测量的。去质子化的鸟嘌呤主要通过脱氨作用（97％）解离，而碳二亚胺（HNCNH）和/或氰胺（NH2CN）和异氰酸（HNCO）损失较小。通过损失氰化氢和/或异氰化物（HCN / HNC; 90％）和碳二亚胺（HNCNH）和/或氰胺（NH2CN; 10％）使去质子化的腺嘌呤片段。串联质谱（MS）实验表明，去质子化的鸟嘌呤片段会丢失其他HCN和CO，而去质子化的腺嘌呤片段会依次丢失HNC和HCN。这项研究中观察到的每个中性片段均已在ISM中检测到，突出了在此类环境中形成此类碱基的潜力。最后，丰富的碎片离子的酸度在实验中被包围。在B3LYP / 6-311 ++ G（d，p）的理论水平上进行了理论计算，以描绘解离的机理并分析了这些CID过程的反应物，中间体，过渡态和产物的能量。

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