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Electrospray ionization mass spectrometric studies on the characteristic fragmentation of Asp/cyclen conjugates
Author(s) -
Ma Chunying,
Li Chao,
Luan Xingrong,
Zhang Jin,
Qiao Renzhong,
Zhao Yufen
Publication year - 2014
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6822
Subject(s) - cyclen , chemistry , electrospray ionization , protonation , mass spectrometry , tandem mass spectrometry , collision induced dissociation , dissociation (chemistry) , amide , fragmentation (computing) , stereochemistry , ion , chromatography , organic chemistry , computer science , operating system
RATIONALE Differentiation and structural characterization of Asp/cyclen conjugates by electrospray ionization tandem mass spectrometry (ESI‐MS n ) are significantly important for their biomedical application. Hence, the present study is conducted. METHODS The fragmentations of Asp/cyclen conjugates generated by positive ion mode electrospray ionization were examined here by low‐energy collision‐induced dissociation (CID). ESI‐MS n spectra of cyclen were acquired to confirm cyclen contraction products derived from the studied compounds. The fragments derived from the Asp/cyclen conjugates were proved by deuterium‐exchange experiments. RESULTS Asp/cyclen conjugates displayed characteristic dissociation pathways, including cleavages of amide bonds, loss of NH 3 and cyclen contraction pathways. It was observed that cleavages of C‐terminal amide bonds generated b 2 and b 2 + H 2 O ions from the protonated CyclenAspAspAsp and a b 1 + H 2 O ion from the protonated CyclenAspAsp. In addition, various cyclen contraction products were also observed. CONCLUSIONS In ESI‐MS n spectra of studied compounds, fragments of b n‐1 + H 2 O or cyclic anhydride were generated due to facile mobilization of C‐terminal or side‐chain COOH protons. In addition, the cyclen contraction products were detected. These results might provide sufficient information for the identification of Asp/cyclen conjugates by mass spectrometry. Copyright © 2014 John Wiley & Sons, Ltd.