The gas phase fragmentation reactions of singly charged angiotensin II (AngII, DRVYIHPF) and the ozonolysis products AngII+O (DRVY*IHPF), AngII+3O (DRVYIH*PF), and AngII+4O (DRVY*IH*PF) were studied using SID FT-ICR mass spectrometry and molecular dynamics. Oxidation of Tyr (AngII+O) leads to an additional low-energy charge-remote selective fragmentation channel resulting in the b4 fragment ion. Modification of His leads to a series of new selective dissociation channels. For AngII+3O and AngII+4O, the formation of [MH+3O]+-45 and [MH+3O]+-71 are driven by charge-remote processes while it is suggested that the b5 and [MH+3O]+-88 fragments are a result of charge-directed reactions. Energy-resolved SID experiments and RRKM modeling were able to provide insight into the energetics of the lowest energy fragmentation channel for each of the parent ions. Destabilization of the ozonolysis products was found to be strictly due to entropic effects. Mechanistic details for each of the new dissociation pathways were determined by relating the SID FT-ICR MS results to parent ion conformations samples using molecular dynamics.
Revised: September 10, 2010 |
Published: September 8, 2009
Citation
Spraggins J.M., J.A. Lloyd, M.V. Johnston, J. Laskin, and D.P. Ridge. 2009.Fragmentation Mechanisms of Oxidized Peptides Elucidated by SID, RRKM Modeling and Molecular Dynamics.Journal of the American Society for Mass Spectrometry 20, no. 9:1579-1592.PNNL-SA-61952.doi:10.1016/j.jasms.2009.04.012