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Spectroscopy
Volume 23 (2009), Issue 3-4, Pages 131-139
http://dx.doi.org/10.3233/SPE-2009-0388

ESI-MSn study on the fragmentation of protonated cyclic-dipeptides

Yan-Chun Guo,1 Shu-Xia Cao,1,3 Xiang-Kun Zong,1 Xin-Cheng Liao,1 and Yu-Fen Zhao1,2

1The Key Laboratory of Chemical Biology and Organic Chemistry, Department of Chemistry, ZhengZhou University, Henan, China
2The Key Laboratory for Bioorganic Phosphorus Chemistry and Chemical Biology, Ministry of Education, Department of Chemistry School of Life Sciences and Engineering, Tsinghua University, Beijing, China
3The Key Laboratory of Chemical Biology and Organic Chemistry, Department of Chemistry, ZhengZhou University, Henan 450052, China

Copyright © 2009 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Cyclic dipeptides are relatively simple compounds that can exhibit a great variety of important biological activities. The fragmentation pathways of protonated cyclic dipeptides have been studied by electrospray ionization multistage mass spectrometry (ESI-MSn). The mass spectra studies of the cyclic dipeptides showed that the cyclic dipeptides with the similar substituents, the side chains of amino acid residues at the diketopiperazine ring, followed the same fragmentation pathway. In the fragmentation spectra of protonated cyclic dipeptides, some characteristic fragment ions were observed and could be used to distinguish the cyclic dipeptides. The hydrogen/deuterium (H/D) exchange experiment and the high-resolution mass spectrometry (Q-TOF) were used to verify and rationalize the proposed fragmentation pathways. These observations may have some potential applications in the structural elucidation and interpretation of the mass spectra of homologous compounds.