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Comparison of the isomeric α‐amino acyl adenylates and amino acid phosphoramidates of adenosine by electrospray ionization tandem mass spectrometry
Author(s) -
Gao Xiang,
Zeng Zhiping,
Xu Pengxiang,
Tang Guo,
Liu Yan,
Zhao Yufen
Publication year - 2010
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.4862
Subject(s) - chemistry , phosphoramidate , electrospray ionization , tandem mass spectrometry , amino acid , stereochemistry , medicinal chemistry , mass spectrometry , chromatography , biochemistry
Abstract The isomeric α‐amino acyl adenylates and amino acid phosphoramidates of adenosine were synthesized and analyzed in detail by electrospray ionization tandem mass spectrometry (ESI‐MS n ). In ESI‐MS/MS of α‐amino acyl adenylates, the novel rearrangement ion [cAMP–H] – observed as the most intense signal was formed through the pentacoordinate phosphorus intermediate with a six‐membered ring by nucleophilic attack of the 3'‐hydroxyl group on the phosphorus atom. In contrast, for the amino acid phosphoramidate of adenosine, the phosphorus atom could be attacked not only by the carboxylic group to form the cyclic aminoacyl phosphoramidates (CAPAs), but also by the nitrogen atom on the nucleobase leading to intramolecular phosphoryl group migration. It was found that the sodium ion having multidentate binding ability played an essential role in this characteristic rearrangement. The proposed mechanisms were supported by the MS/MS study, deuterium‐labeled experiments, high‐resolution tandem mass spectrometry and moderate calculations at the B3LYP/6‐31G* level. The characteristic fragmentation patterns of α‐amino acyl phosphates and amino acid phosphoramidates allows identification of stereoisomers when either the phosphorylation is at the N ‐terminus or C ‐terminus of amino acids. Copyright © 2010 John Wiley & Sons, Ltd.