Fujihara Akimasa, Maeda Naoto, Hayakawa Shigeo
Department of Chemistry, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan,
Orig Life Evol Biosph. 2014 Apr;44(2):67-73. doi: 10.1007/s11084-014-9370-9. Epub 2014 Oct 29.
Photostability of cold gas-phase tryptophan (Trp) enantiomers in L-serine (L-Ser) clusters at 8 K as a model for interstellar molecular clouds was examined using a tandem mass spectrometer containing a cold ion trap to investigate the hypothesis that homochirality in gas-phase Ser clusters promotes the enantiomeric enrichment of other amino acids via enantiomer-selective photolysis with linearly polarized light. In the UV excitation of heterochiral H(+) (L-Ser) 3(D-Trp), the CO2-eliminated product in the cluster was observed. In contrast, the photodissociation mass spectrum of homochiral H(+)(L-Ser)3(L-Trp) showed that photolysis of amino acids in the cluster did not occur due to the evaporation of L-Ser molecules. In the spectra of the homochiral H(+)(L-Ser) (L-Trp) and heterochiral H(+)(L-Ser) (D-Trp), the evaporation of L-Ser was the primary reaction pathway, and no difference between the L- and D-enantiomers was observed. The findings confirm that when 3 L-Ser units are present in the cluster, the photolytic decomposition of Trp is enantiomerically selective.
使用包含冷离子阱的串联质谱仪，研究了作为星际分子云模型的8K下L-丝氨酸（L-Ser）簇中冷气相色氨酸（Trp）对映体的光稳定性，以探究气相Ser簇中的同手性是否通过线性偏振光的对映体选择性光解促进其他氨基酸的对映体富集这一假设。在异手性H(+)（L-Ser）3（D-Trp）的紫外激发中，观察到簇中消除CO2的产物。相比之下，同手性H(+)（L-Ser）3（L-Trp）的光解离质谱表明，由于L-Ser分子的蒸发，簇中氨基酸的光解未发生。在同手性H(+)（L-Ser）（L-Trp）和异手性H(+)（L-Ser）（D-Trp）的光谱中，L-Ser的蒸发是主要反应途径，未观察到L-和D-对映体之间的差异。研究结果证实，当簇中存在3个L-Ser单元时，Trp的光解分解具有对映体选择性。
