Purification and properties of proteolytic enzymes from thermophilic actinomycetes

The enzymes isolated from two selected cultures of thermophilic actinomycetes-Thermomonospora fusca (A 29) and Thermoactinomyces vulgaris (A 60)-possess proteolytic activity. The enzymes were purified more than 35- to 40-fold and showed three bands each upon cellulose acetate electrophoresis at several pH values. Based upon Sephadex gel filtration, molecular weights of 21,500 and 23,800 were calculated for the active peaks of the enzymes. The purified enzymes lysed heat-killed cells of gram-positive and gram-negative bacteria, mycobacteria, and fungi and also hydrolyzed casein. The enzymes were most active between a temperature range of 60 and 70 C and pH 8.0 and 9.0, and were significantly inhibited by potassium permanganate, potassium ferricyanide, and iodine.