ИСТИНА

Nowadays, even in the high-developed countries the increase of deceases caused by streptococci, are noted. The fact is connected with an appearance of antibiotic resistant bacterial strains. Bacteriophages, viruses of bacteria, and their lytic enzymes can be considered as potential alternative to the antibioticotherapy. In 1971, the enzyme produced by bacteriophage C1 possessing lytic activity towards Strep A cells, was isolated by V. Fischetti. In the literature, it is referred to Lysin, or N-acetylmuramoyl-L-alanine amidase, or PlyC Lysin. The enzyme (PlyC Lysin) is able to cleave covalent bonds in peptidoglycan part of bacterial cell wall resulting in the effective streptococci cells lysis. However, the enzyme has low temperature stability. The aim of the present study was to improve the PlyC Lysin stability. Several approaches were developed: the use of micelle-forming matrices, cross-linking agents, and their combination. Since the enzyme was found to self-assemble into an octamer, the use of cross-linking agents could be helpful to improve the enzyme stability. Several bi-functional cross linking reagents (BS3, glutaraldehide, DMA, DMS, EDC, sulfo-NHS) at different pH with different agent/protein ratio were used. Under enzyme optimal conditions (20 mM K-phosphate buffer, pH 6,3), the stability of modified enzyme at 37oC was checked in comparison with the initial (native) PlyC Lysin. Significant increase (several times) in the enzyme stability was found upon its modification. Polyelectrolytes and micelle-forming compounds were found to help stabilize PlyC Lysin for several months during shelf-life storage at RT. The study was performed to find out the effect of each component; the importance of the reagent/protein ratio was shown. The combination of the enzyme modification and its accommodation into micelle-forming matrices shows promises in using PlyC Lysin as a component of commercially available oral hygiene liquids.