THE INTERACTION OF MASTOPARAN-B FROM VENOM OF A HORNET VESPA-BASALIS WITH PHOSPHOLIPID MATRICES

Mastoparan B (MP-B) that is a novel MP isolated from the hornet Vespa basalis, was studied as compared with MP, in terms of interaction with phospholipid bilayer and antimicrobial activity. MP-B has more hydrop hilic amino acid residues in hydrophilic face of amphiphilic alpha-hel ical structure than MP. The both peptides exhibited considerably diffe rent effect on interaction with lipid bilayers, e.g. their conformatio n in the presence of acidic and neutral liposomes, dye-release ability from encapsulated liposomes, but on the whole the interaction mode wa s similar. On antimicrobial activity, MP had a strong activity against Gram-positive bacteria but no against Gram negative ones. Contrary to this, MP-B had a strong activity against Gram-positive and potent aga inst Gram-negative ones. Since both peptides have almost same residues on the hydrophobic side, such more hydrophilic surface on the molecul e seems to lead to the subtle change in its interaction with membranes , resulting in the alternation in its biological activity.