Biomedical subjects
Publications and source records attributed to G I Petrov.
As revealed, autolytic enzymatic system of hemolytic streptococcus, group A, expressed the maximal activity at the end of the exponential growth phase. Autolysis was accompanied by the release of N-acetylaminosugars and of free amino group. Optimal conditions for the lytic system function were chosen (composition, ionic strength, and buffer pH). The activating action of trypsin and chemotrypsin was demonstrated.
More than 80 cultures of actinomycetes belonging to different taxanomic groups were studied with a purpose of screening actinomycetes actively producing enzymes lyzing the cell walls of group A streptococci. 31 strains of the actinomycetes producing enzymes which lyzed the cell walls by 20-50 and 60-80 per cent within 1 and 4 hours respectively were selected. The proteolytic activity of the enzymes produced by these strains was also studied. It was shown that 4 cultures, i.e. Actinomyces albus, strains 6 and 9, Actinomyces levoris, strain 29 and Actinomyces gibsonii, strain 42 were of interest as organisms producing enzymes which lyzed the streptococcal cell wall without impairing its antigenic components.
The effect of Streptomyces griseus pronase on Streptococcus group A cell walls was studied. Cell walls were shown to be lysed by pronase, the lysis level being dependent on the molarity of the potassium-phosphate buffer used. With an increase in the buffer molarity from 0.005 M to 0.05 M lysis of cell walls decreased from 70-80% to 30%. By DEAE-cellulose chromatography lysates were separated into two fractions the first of which contained a group specific polysaccharide. A preparative method of obtaining a group specific polysaccharide of Streptococcus group A using Streptomyces griseus pronase under mild conditions is described.
The composition of the enzyme complex produced by Actinomyces levoris which exhibits lytic action on the cell walls of Streptococcus lactis was studied by gel filtration on Sephadex G-25, ion exchange chromatography and isoelectric focusing. The complex was found to contain at least seven enzymes having different isoelectric points and substrate specificity. The enzymes were divided into three groups. (1) The enzyme with pI 10.2 seems to be a specific glucosidase; it possesses a high activity of the cell wall lysis and lacks a proteolytic activity. (2) The enzymes with pI 9.2 and 9.0 are, apparently, specific lytic proteases; they display both lytic and proteolytic activities. (3) The enzymes with pI 10.0, 9.5, 5.7 and 4.2 are, presumably, non-specific lytic proteases; they have a low lytic activity and a high proteolytic activity.