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Neuraminidase isolated from Yersinia pestis [correction of the plaque microbe] and purified has been studied for its effect on the peritoneal leukocytes of the white mice with results presented. Neuraminidase exerted the insulin-like effect on the peritoneal leukocytes of the white mice and this effect depended on the used dose. The priming of leukocytes by neuraminidase preparation was accompanied by the sharp increase of hydrogen peroxide production under effect of the capsule antigen of the plaque microbe and, apparently, by the appearance of additional binding sites for the adhesion piles of the plaque agent.

The intracellular form of neuraminidase has been detected in E. coli and Proteus vulgaris. Neuraminidase has been isolated from E. coli HB 101 cells and purified 118-fold. Some physico-chemical properties of this enzyme have been studied.

The biological action of Y. pestis adenylate cyclase on peritoneal leukocytes of guinea pigs has been studied by means of chemiluminescence. Y. pestis adenylate cyclase is supposed to contribute to the "oxidation" explosion of phagocytes in plague.

The quantitative method for determination of penicillinacylase activity is described. The method is based on detection of phenylacetic acid (PAA) formed during hydrolysis of benzylpenicillin. PAA is extracted with toluol and nitrated with potassium nitrate solution in concentrated sulphuric acid followed by reduction of nitrophenylacetic acid into aminophenylacetic acid with zinc powder. Aminophenylacetic acid interacts with p-dimethylaminobenzaldehyde in acid medium forming a coloured compound (Schiff base). The optic density of the latter was determined with spectrophotometer SF-16 at 430 nm. The method was used for determination of acylase in Yersinia species and some other bacteria.