A Comprehensive Proteomic Study of the Skin Secretions of the Frog Lithobates spectabilis.

Disulfide C-terminal loop fragments derived from AMPs and the presence of peptidases have been previously reported in the skin secretions of different amphibians. However, there are only a few studies on the identification of enzymes in frog skin secretion based on the primary structure of these proteins. Similarly, little data exist regarding the identification of disulfide C-terminal loops at large scale.

Analysis of sulfated peptides from the skin secretion of the Pachymedusa dacnicolor frog using IMAC-Ga enrichment and high-resolution mass spectrometry.

Immobilized metal ion affinity chromatography (IMAC) has been widely used for the enrichment of phosphopeptides, whereas no report exists describing the use of IMAC columns for the enrichment of sulfopeptides. In this study, we used IMAC-Ga microcolumns for the enrichment of sulfopeptides from a complex mixture of peptides, extracted from skin secretions of the Pachymedusa dacnicolor frog. The enriched fraction obtained by IMAC-Ga was analyzed by liquid chromatograpy/electrospray ionization mass spectrometry (LC/ESI-MS) in an Orbitrap XL and by matrix-assisted laser desorption/ionization time-of-flight time-of-flight (MALDI-TOF/TOF) in an ABI 4800 instrument.