Theoretical Investigation of the Gas Phase Cu+-Activated Fragmentation of D-Alanine

Hai Jun Zhu1,2, Wei Xian Cheng1, Yi Lei Chen1, Huai Cao1, Xiao Gaung Xie3 and Tao Hong Li4,*

1Modern Biological Research Center, Yunnan Univerisity, Kunming 650091, P.R. China

2Quality Supervision and Testing Station, Beijing Municipal Tobacco Company, Beijing 100029, P.R. China

3Department of Chemistry, Yunnan Univerisity, Kunming 650091, P.R. China

4College of Science, Southwest Forestry University, Kunming 650224, P.R. China

*Corresponding author: Fax: +86 871 3863006; Tel: +86 871 3863375; E-mail:


The gas phase Cu+-activated fragmentation of D-alanine was theoretically investigated at B3LYP and MP2 levels. The experimentally observed products can be rationalized by the mechanism as: Cu++D-alanine ® h2 (NH2, C=O) complex ® Ca-COOH bond insertion ® O=C-OH bond insertion ® H migration from -NH2 to -OH ® [CH3CHNH-(H2O)Cu(CO)]+. Dissociations of the final intermediate in different forms produce the products corresponding to loss of H2O, CO and H2O + CO, respectively. Another product channel leading to elimination of HCOOH was also identified but it is energetically less favourable than the first one. By comparing the Cu+ + alanine reaction with previously studied Cu+ + phenylalanine reaction, it was concluded that different a-amino acids may share common reaction mechanisms for the same product channels. Different side chains change the reactivity but do not change the mechanisms significantly.


Cu+, D-Alanine, Insertion, Fragmentation, Theoretical.

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