Photoreaction of<i>rac</i>-Leucine in Ice by Circularly Polarized Synchrotron Radiation: Temperature-Induced Mechanism Switching from Norrish Type II to Deamination
作者:Hideo Nishino、Masahito Hosaka、Masahiro Katoh、Yoshihisa Inoue
DOI:10.1002/chem.201301831
日期:2013.10.4
respectively. Comprehensive product analyses revealed that the CPL‐induced deracemization of Leu proceeds in both acidic and neutral ice matrices even at 21 K, and that the main mechanism switches from Norrish‐type II γ‐hydrogen abstraction to SNi deamination on lowering the temperature. The potential role of the CPL‐induced photodecomposition of amino acids as a source of the enantiomer imbalance in meteorites
认为外星有机物向原始地球的输送触发了生命的起源和随后的进化。实际上,已经在碳质陨石中发现了非陆地来源的对映异构体富集的氨基酸,并且有人提出在外层空间中通过圆偏振光(CPL)进行对映体选择性光分解在初始对映体偏斜中起了一定作用。为了通过实验检验这种可能性并阐明光反应机理,我们研究了左旋和右旋CPL在21–298 K的酸性和中性冰/水介质中消旋亮氨酸(rac -Leu)的光解,以尝试对映体检测富集的D-和L‐Leu,分别。全面的产品分析表明,即使在21 K时,CPL诱导的Leu消酸作用在酸性和中性冰基质中均会发生,并且其主要机理是在降低温度时从Norrish II型γ氢提取转变为S N i脱氨。讨论了CPL诱导的氨基酸光分解作为陨石中对映异构体失衡的潜在作用。