title: Comparison of the isomeric α-amino acyl adenylates and amino acid phosphoramidates of adenosine by electrospray ionization tandem mass spectrometry.
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.
authors.affiliation: Department of Chemistry and The Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P.R. China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Zeng
authors.forename: Pengxiang
authors.initials: P
authors.lastname: Xu
authors.forename: Guo
authors.initials: G
authors.lastname: Tang
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Yufen
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000737:chemistry; D000577:Amides / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry*; D049148:Aminoacylation; D007536:Isomerism; D008956:Models, Chemical; D008968:Molecular Conformation; D010756:Phosphoric Acids / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000577:Amides; D000596:Amino Acids; D010756:Phosphoric Acids; C011067:phosphoramidic acid; D000241:Adenosine