We compared the tandem mass spectra of a range of native and acetylated Ag(+) cationized peptides to determine the influence of the derivatization step on the abundance of the b(n) + 17 + Ag product ions. Using tripeptides, the smallest for which the mechanisms to generate b(2) - 1 + Ag and b(2) + 17 + Ag products are both operative, we found that in most cases acetylation causes an increase in the abundance of the C-terminal rearrangement ion, b(2) + 17 + Ag, relative to the rival N-terminal rearrangement ion, b(2) - 1 + Ag. The presence of a free amino group to bind to the metal ion significantly influences the relative abundances of the product ions. We propose a mechanism for the formation of the b(n) + 17 + Ag that is based on the formation of a five-membered oxazolidin-5-one and tetrahedral carbon intermediate that may collapse to a peptide upon release of CO and an imine, aided by the fact that the ring formed during C-terminal rearrangement is both a hemiacylal and hemiaminal. We also identified an influence of amino acid sequence on the relative abundances of the b(n) + 17 + Ag and b(n) - 1 + Ag product ions, whereby bulky substituents located on the alpha-carbon of the amino acid to the C-terminal side of the cleavage site apparently promote the formation of the b(n) + 17 + Ag product over b(n) - 1 + Ag when the amino acid to the N-terminal side of the cleavage site is glycine. The latter ion is the favored product, however, when the bulky group is positioned on the alpha-carbon of the amino acid to the N-terminal side of the cleavage site.