INVESTIGATIONS OF MEMBRANE-PEPTIDE INTERACTIONS FOR SOLITARY WASP PEPTIDE TOXINS

Alves, D.S.(1), Fossey, M.(2), Ruggiero, j.(2), Filgueira, W.(2), Konno, K.(1), Palma, M.(1).

(1)CEIS, UNESP, Rio Claro, (2)Department of Physics, UNESP, São José do Rio Preto.

Anoplin and EMP-AF are peptides that were isolated from the venoms of the solitary wasps, that showed antimicrobial, hemolytic and mast cell degranulation activities. Earlier studies revealed that the interactions of peptides with phospholipids and polysaccharides are very important to understand the mechanisms of these peptides. The pore formation on the bacteria membrane is related to the structure of the peptides. Studies demonstrated that the a-helical conformation induce the penetration of the peptide into the cell. The Glycosaminoglycan Heparan Sulfate (HS) occurs on the surface of the most cells as proteoglycans side chains. Heparin can be described as a highly sulfated type of HS found in the mast cell granules. We used heparin in this study due to its known interaction with peptides and its natural occurrence on mast cells. The complex interaction heparin, peptides and liposomes was studied by using Circular Dicroism (CD). The model of liposomes that we used was Small Unilamellar Vesicles (SUVs) and the lipids were DMPC and DMPG. The presence of heparin seems to induce a-helical conformations both for Anoplin and EMP-AP peptides, even in aqueous solutions, suggesting a feed-back mechanism when these peptides start to induce mast cell degranulation delivering heparin from the granules. The results of the CD spectra of Anoplin and EMP-AF in presence of different compositions of phospholipids indicate a high percentage of a-helical conformation it is required to observe the interactions of anoplin and EMP-AF with the membranes. The results of the present investigation surely present new understanding about the mechanism of interaction peptide-membrane, mainly to explain the antibiotic effect of these peptides and their involvement with the inflammatory process.

CORRESPONDENCE TO:

DaianeSantana Alves, Avenida 24-A n° 770 ap. 2, Rio Claro, SP, CEP: 13506-692, Brasil, Email: daianesa@hotmail.com