[Characterization of a protease from Thermoactinomyces vulgaris (thermitase). 1. Purification of thermitase].

The paper deals with the purification of the microbial protease preparation "thermitase" (submerged cultivation of Thermoactinomyces vulgaris; treatment of culture filtrate with ethanol or Na2SO4, vacuum drying of precipitate). The crude substance was purified by column chromatography on Sephadex G-75, DEAE-Cellulose and Sephadex G-50. The proteolytically active fractions were in each case united, freeze dried and tested for protein components and protease activity by gel electrophoresis. After passage of the third column the isolated protease (4.5 fold enrichment in the specific activity) was further characterized. The electropherogram (pH 8.9) presented a protease band moving to the anode which was accompanied by 2 very weak protease bands. Furthermore there could be detected a very active protease band (main component of Thermitase) as well as a side band with lower activity both moving to the cathode. The freeze dried preparation contained 85% protein and 4% carbohydrates (glucose as single monomer component after acid hydrolysis). A molecular weight of 11,000 was determined by chromatography on Sephadex G-75. This value is critically discussed. Hints are given for autolytic processes taking place during the purification procedure.