Atmospheric pressure photoionization of peptides
Abstract
In this work, fragmentations of peptides under atmospheric pressure photoionization conditions are further investigated for a model peptide. In the positive ion mode, intensive fragmentations are observed, mainly ascribed to c-sequence ions along with less abundant a- and b- type ions. The same features and c- ion series are reported for the negative ion mode, thereby suggesting a common mechanistic origin for the fragmentation in both ion modes. Moreover, it is shown that ECD-like fragmentation under APPI conditions may retain non-covalent adducts. This interesting property positions APPI as a promising ECD-like technique for in-source top down sequencing. (C) 2010 Elsevier B.V. All rights reserved.