[Comparative study of proteolytic enzyme preparations of the actinomycete Streptomyces spheroides and its mutant].

Preparations of proteolytic enzymes with high fibrinolytic and thrombolytic activities were isolated from the cultural broth filtrates of Streptomyces spheroides and its mutant by precipitation with ammonium sulfate, dialysis and freeze-drying. The fibrinolytic and thrombolytic activities of the enzymes produced by the mutant are 5.6 and 6 times higher, respectively, than those of the parent strain. Moreover, the enzymes of the mutant have an elevated stability in the alkaline pH region, the optimum of their activities is also shifted to the alkaline pH region, they are more resistant to the action of blood plasma inhibitors and more sensitive to the action of high temperatures. As was shown using isoelectric focusing in a sucrose density gradient, the preparations of both the parent and mutant strains contain several proteolytic enzymes (or their groups) with acid, neutral and alkaline isoelectric points.