Thermal Formation of Homochiral Serine Clusters and Implications for the Origin of Homochirality
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- 作者：Pengxiang Yang ; Ruifeng Xu ; Sergio C. Nanita ; R. Graham Cooks
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：December 27, 2006
- 年：2006
- 卷：128
- 期：51
- 页码：17074 - 17086
- 全文大小：810K
- 年卷期：v.128,no.51(December 27, 2006)
- ISSN：1520-5126
文摘
Spontaneous assembly of amino acids into vapor-phase clusters occurs on heating the solidcompounds in air. In comparison to the other amino acids, serine forms clusters to an unusual extent,showing a magic number octamer on sublimation; this octamer can be ionized and characterized by massspectrometry. Two isomers of the vapor-phase serine octamer are generated, the minor one at 130 
Cand the major at 220 C. The higher temperature cluster shows a strong homochiral preference, as confirmedby isotopic labeling experiments. This serine cluster, like that generated earlier from solution in electrosprayionization experiments, undergoes gas-phase enantioselective substitution reactions with other amino acids.These reactions transfer the chirality of serine to the other amino acid through enantioselective incorporationinto the octamer. Other serine pyrolysis products include alanine, glycine, ethanolamine, and smalldipeptides, and many of these, too, are observed to be incorporated into the thermally formed serineoctamers. Chiral chromatographic analysis confirmed that L-serine sublimation produced DL-alanine, glycine,and ethanolamine, while in the presence of hydrogen sulfide, L-serine yielded L-cysteine. The datademonstrate that sublimation of serine under relatively mild conditions yields chirally enriched serineoctamers and that the chiral preference of the starting serine can be transferred to other compounds throughcluster-forming chemical reactions.
Cand the major at 220 C. The higher temperature cluster shows a strong homochiral preference, as confirmedby isotopic labeling experiments. This serine cluster, like that generated earlier from solution in electrosprayionization experiments, undergoes gas-phase enantioselective substitution reactions with other amino acids.These reactions transfer the chirality of serine to the other amino acid through enantioselective incorporationinto the octamer. Other serine pyrolysis products include alanine, glycine, ethanolamine, and smalldipeptides, and many of these, too, are observed to be incorporated into the thermally formed serineoctamers. Chiral chromatographic analysis confirmed that L-serine sublimation produced DL-alanine, glycine,and ethanolamine, while in the presence of hydrogen sulfide, L-serine yielded L-cysteine. The datademonstrate that sublimation of serine under relatively mild conditions yields chirally enriched serineoctamers and that the chiral preference of the starting serine can be transferred to other compounds throughcluster-forming chemical reactions.