Bacteriolytic activity of human interleukin-2.

In this paper we report the discovery of bacteriolytic activity of an immune system cytokine mediator, interleukin-2. Bacteriolytic activity of interleukin-2 was compared with a well-known bacteriolytic enzyme - chicken egg white lysozyme - by monitoring the lysis of the Gram-negative bacterium Escherichia coli, the Gram-positive coccus Micrococcus luteus, and the Gram-positive spore-forming bacillus Bacillus subtilis. It was found that interleukin-2 has greater specificity to the Gram-negative bacterium E. coli than does lysozyme. In contrast to chicken egg white lysozyme, interleukin-2 does not lyse the Gram-positive coccus M. luteus and the Gram-positive spore-forming bacillus B. subtilis. These results give a new understanding of the biological functions of interleukin-2, a regulatory protein that plays a role in oncological and infectious diseases.

[Bacteriolytic enzymes of blood plasma from sheep].

In the present work the studies ofbacteriolytic factors from sheep blood plasma have been performed. Three novel enzymes have been identified and characterized. Two of them have a molecular weight 15 +/- 2 kDa and able to lyse the gram-negative Escherichia coli bacteria. The third enzyme has a molecular weight 34 +/- 4 kDa and is able to lyse both gram-negative Escherichia coli and gram-positive Micrococcus luteus bacteria. The bacteriolytic reactions have been studied for all three enzymes; particularly, pH-optima have been identified with respect to the substrate. To identify the enzymes trypsinolysis and consequent MALDI-TOF mass spectrometry studies were performed. The results were compared to data from publicly available databases, such as Swiss-Prot, NCBI, MSDB.

Enzymes of SPZ7 phage: isolation and properties.

Bacteriophage enzyme preparations exolysin and endolysin were studied. Exolysin (a phage-associated enzyme) was obtained from tail fraction and endolysin from phage-free cytoplasmic fraction of disintegrated Salmonella enteritidis cells. A new method for purification of these enzymes was developed, and their molecular masses were determined. The main catalytic properties of the studied enzymes (pH optimum and specificity to bacterial substrates) were found to be similar. Both enzymes lyse Escherichia coli cells like chicken egg lysozyme, but more efficiently lyse S. enteritidis cells and cannot lyse Micrococcus luteus, a good substrate for chicken egg lysozyme. Similar properties of exolysin and endolysin suggest that these enzymes are structurally similar or even identical.

Lysis of Escherichia coli cells by lysozyme: discrimination between adsorption and enzyme action.

The key factors of enzymatic lysis of cells are the interaction between the enzyme and the cell - catalytic and non-catalytic adsorption of enzyme on cell surface. Here, the studies of lysis of intact Escherichia coli cells by chicken egg white lysozyme were performed. It was found that the ionic strength has a dual effect onto the system. On the one hand, the desorption constant of the enzyme increases with the increase of the solution ionic strength, which results in a better enzyme performance. On the other hand, due to the higher osmosis, the cell lysis rate decreases with the increasing of ionic strength of the system. It was found that pH 8.6 and 30 mM NaCl are optimal conditions for lysis of E. coli cells by lysozyme.