Structural and functional characterization of the porcine proline–rich antifungal peptide SP-B isolated from salivary gland granules

✍ Scribed by T. Cabras; R. Longhi; F. Secundo; G. Nocca; S. Conti; L. Polonelli; C. Fanali; R. Inzitari; R. Petruzzelli; I. Messana; M. Castagnola; A. Vitali

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 250 KB
• Volume: 14
• Category: Article
• ISSN: 1075-2617
• DOI: 10.1002/psc.914

✦ Synopsis

Abstract

A 1905‐Da cationic proline‐rich peptide, named SP‐B, was recently isolated by our group as the main component of salivary gland granules, and its primary sequence fully characterized by means of automated Edman sequencing and LC‐MS/MS tools. In the present study SP‐B is shown to possess antifungal activity when challenged with strains of Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus, while only negligible antibacterial activity was detected. Furthermore, SP‐B was found to be non‐cytotoxic when tested on fibroblast cell lines. To obtain information regarding its structure affinity, capillary electrophoresis (CE), circular dichroism (CD) and attenuated total reflection (ATR)‐FT/IR experiments were performed. CE revealed a pH dependence of the hydrodynamic radial dimensions both in aqueous and 2,2,2‐trifluoroethanol solutions. CD and ATR‐FT/IR measurements confirmed the structure–pH relationship, revealing a secondary structure composed of mixed proportions of polyproline‐II, unordered and turn motifs, the last being more evident in the zwitterionic form of the peptide. From these findings SP‐B peptide could be classified as a new member of the proline‐rich antimicrobial peptide family. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.