Analysis of skin derived peptides from the Cuyaba Dwarf Frog Physalaemus nattereri by off-line LC MALDI MS/MS

We have investigated the potential for analysis of the complex peptide mixtures secreted from frog skin using off-line LC-MALDI MS/MS. Since only limited information about the sequence of such peptides is available, de novo sequencing followed by Blast search was needed. An automated workflow has been applied based on automated collection of the chromatographic fractions on the MALDI target followed by automated recording of the MS/MS spectra of the 10 most intense peaks in each fraction. The MS/MS spectra were submitted to de novo sequencing by the Peaks software and searched for potential matches in an amphibian database extracted from UniProt. A number of known skin secreted peptides as well as precursor proteins for these were identified. However, most of the recorded MS/MS data and deduced sequences did not result in matches with the databases. These sequences might serve as a reference for future studies of peptides secreted from frogs.