title: Structural and functional studies on a proline-rich peptide isolated from swine saliva endowed with antifungal activity towards Cryptococcus neoformans.
abstract: A proline-rich peptide of 2733Da, isolated from pig parotid granule preparations was tested against different pathogenic fungi. It showed interesting antifungal activity towards a clinical isolate of Cryptococcus neoformans, with an EC(50) of 2.2μM. Neither cytotoxic nor haemolytic effects were observed towards mammalian cells. Circular dichroism and infrared spectroscopic studies showed that the peptide adopted a combination of polyproline type-II, β-turn and unordered conformations at physiological temperatures. Temperature dependent experiments evidenced a tendency to adopt a polyproline-II helix conformation. From experiments with lipid vesicles, Neutral Red Uptake (NRU), haemolytic assays, and confocal microscopy studies, it could be hypothesized that the peptide may exert its antifungal effect by interacting with an intracellular target rather than through membrane damage.
authors.affiliation: Dipartimento di Scienze Biomediche, University of Parma, Parma, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Conti
authors.forename: Giorgia
authors.initials: G
authors.lastname: Radicioni
authors.forename: Tecla
authors.initials: T
authors.lastname: Ciociola
authors.forename: Renato
authors.initials: R
authors.lastname: Longhi
authors.forename: Luciano
authors.initials: L
authors.lastname: Polonelli
authors.forename: Rita
authors.initials: R
authors.lastname: Gatti
authors.forename: Tiziana
authors.initials: T
authors.lastname: Cabras
authors.forename: Irene
authors.initials: I
authors.lastname: Messana
authors.forename: Massimo
authors.initials: M
authors.lastname: Castagnola
authors.forename: Alberto
authors.initials: A
authors.lastname: Vitali
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000935:Antifungal Agents / Q000032:analysis / Q000494:pharmacology*; D002942:Circular Dichroism; D003455:Cryptococcus neoformans / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000166:cytology; D006461:Hemolysis; D006801:Humans; D051379:Mice; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal / Q000379:methods; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D011487:Protein Conformation; D012463:Saliva / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013053:Spectrophotometry / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013552:Swine; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D000935:Antifungal Agents; D010455:Peptides; C011083:polyproline; D011392:Proline