crabrolin and Hemolysis

The venom of insects like bee, hornet and wasp contain peptides that exhibit potent biological activities. Many of these peptides are composed of 13-26 residues and are thus accessible through chemical synthesis as well as amenable to studies directed toward structure-function correlations. In this report, we describe antibacterial and hemolytic activities of crabrolin: FLPLILRKIVTAL-NH2, a 13-residue-peptide present in the venom of the hornet Vespa crabro and related peptides. The analogs were chosen so that the role of proline and positively charged amino acids in modulating biological activities could be evaluated. Our results indicate that, although helical conformation is necessary for hemolytic activity, it is not a prerequisite for antibacterial activity. Appropriately positioned, charged and hydrophobic residues and overall hydrophobicity appear to determine antibacterial activity. The discovery of a large number of host-defense peptides in a variety of species in recent years offers a large repertoire of molecules that can be "engineered" based on biophysical principles to yield molecules with specific activities.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Chromatography, High Pressure Liquid; Circular Dichroism; Erythrocytes; Hemolysis; Microbial Sensitivity Tests; Oligopeptides; Protein Conformation; Protein Structure, Secondary; Rats; Wasp Venoms

Two peptides rich in hydrophobic amino acids have been isolated from venom sacs of the European hornet, Vespa crabro. One peptide (P-2) is structurally and functionally related to the tetradecapeptide mastoparan and has been named mastoparan C. Leu-Asn-Leu-Lys-Ala-Leu-Leu-Ala-Val-Ala-Lys-Lys-Ile-LeuNH2. The other (P-1) is a tridecapeptide with a new sequence: Phe-Leu-Pro-Leu-Ile-Leu-Arg-Lys-Ile-Val-Thr-Ala-LeuNH2 which we have named crabrolin. The peptide releases histamine from rat peritoneal mast cells with a threshold of approximately 2.5 micrograms/ml (congruent to 8 microM). Crabrolin also facilitates the action of purified phospholipase A2 from different sources, but it is not quite as active as mastoparan. It is clearly less active than mastoparan in lysing erythrocytes, and it does not release amylase from dispersed guinea pig pancreatic acini. Given its unique sequence, the principal effect of crabrolin may be neither mast cell degranulation nor phospholipase facilitation, but a yet undiscovered action.

Topics: Amino Acid Sequence; Animals; Bee Venoms; Guinea Pigs; Hemolysis; Histamine Release; Hymenoptera; Mast Cells; Pancreas; Peptide Fragments; Phospholipases; Phospholipases A; Phospholipases A2; Rats; Snakes; Swine; Trypsin; Wasp Venoms; Wasps