Resonant electron capture by some amino acids and their methyl esters.
Resonant electron capture by some amino acids and their methyl esters.
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DOI：
10.1021/ja058464q
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发表时间：
2006-04
影响因子：
15
通讯作者：
Y. Vasil’ev;B. Figard;V. G. Voinov;D. Barofsky;M. Deinzer
中科院分区：
文献类型：
--
作者：
Y. Vasil’ev;B. Figard;V. G. Voinov;D. Barofsky;M. Deinzer
脂肪族和芳香族氨基酸及其甲酯的共振电子俘获质谱图显示在低能区有强烈的[M-H](-)负离子。离子的形成是由低能pi*o共振态介导的预解离机制的结果。根据量子化学计算，甲基化对电子结构的影响一般很小，但甲酯的相应离子[M-Me](-)只有在较高的共振能下才能确定。芳香族氨基酸的特征是一个额外的低能裂解通道，与侧链丢失的负离子的产生有关。能量越高，侧链上的互补负离子产生的效率越高。这些结果对生物系统具有重大意义，因为它们表明，氨基酸可以作为辐射防护剂，因为它们被发现可以有效地使电子热化。
Resonant electron capture mass spectra of aliphatic and aromatic amino acids and their methyl esters show intense [M-H](-) negative ions in the low-energy range. Ion formation results from a predissociation mechanism mediated by the low-energy pi*oo resonant state. Methylation in general has little influence on the electronic structure according to quantum chemical calculations, but the corresponding ions from the methyl esters, [M-Me](-), could be ascertained to arise only at higher resonance energies. Aromatic amino acids are characterized by an additional low-energy fragmentation channel associated with the generation of negative ions with loss of the side chain. The complementary negative ions of the side chains are more efficiently produced at higher energies. The results have significant implications in biological systems as they suggest that amino acids can serve as radiation protectors since they have been found to efficiently thermalize electrons.