Antibacterial Non-Glycosidase Activity of Invertebrate Destabilase-Lysozyme and of Its Helical Amphipathic Peptides

Background: Since bactericidal properties of some lysozymes are independent of their glycosidase activity, we have investigated this phenomenon for destabilase-lysozyme (DL) from medicinal leech (Hirudo medicinalis). Methods: Glycosidase activity was determined on Micrococcus luteus, non-enzymatic antibacterial activity of heat-treated DL and of synthetic peptides α1, α2 and α3 (fragments of its primary structure) on M. luteus, Escherichia coli, Bacillus brevis and Streptomyces chrysomallus. Results: Glycosidase activity disappeared after the heating of native DL at 100°C for 40 min. Antibacterial activity of heat-treated DL for M. luteus MDMSU128 and MDMSU140 expressed as minimal inhibitory concentration was 9.8·10–8 and 12·10–8 M, respectively, and to E. coli MDMSU52 11·10–8M. Antibacterial activity of synthetic peptide α1 for M. luteus MDMSU128 and for E. coli MDMSU52 was 8.3·10–5 and 4.9·10–5M, respectively. Conclusion: DL is the first invertebrate lysozyme with combined enzymatic and non-enzymatic antibacterial action.