Structural and functional characterization of the porcine proline-rich antifungal peptide SP-B isolated from salivary gland granules.
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.
Cabras
T
T
Department of Sciences Applied to Biosystems, University of Cagliari, Cittadella Universitaria, Monserrato I-09042, Cagliari, Italy.
Longhi
R
R
Secundo
F
F
Nocca
G
G
Conti
S
S
Polonelli
L
L
Fanali
C
C
Inzitari
R
R
Petruzzelli
R
R
Messana
I
I
Castagnola
M
M
Vitali
A
A
D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D004745:Enkephalins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D011392:Proline / Q000737:chemistry*; D011498:Protein Precursors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D012469:Salivary Glands / Q000737:chemistry*; D034421:Sus scrofa
D000935:Antifungal Agents; D004745:Enkephalins; D011498:Protein Precursors; C056943:peptide B; D011392:Proline