Partial purification and characterization of Rhizomucor miehei protease from wild-type and mutated strains

Characteristics of the partially purified Rhizomucor miehei proteases from the wild-type isolate (Rm4) and novel microwaves-induced mutant (MW150) were studied. Using SDS-PAGE technique, the molecular weights of Rm4 and MW150 proteases were estimated at 39.77 kDa, and 40.62 kDa, respectively. Maximum milk-clotting activity (MCA) was achieved at 57.5 °C, pH 5, and 9 g/L CaCl 2. Maximum proteolytic activity (PA) was achieved at 57.5 °C, and pH 4. Both enzymes were stable at pH values ranging from 3 to 7 for 48 h and temperatures of 50 °C and 60 °C for 24 h and 15 min, respectively. The effect of NaCl by stimulating MCA and inhibiting PA. Maximum PA of Rm4 and MW150 proteases was achieved using 4 % and 2 % casein, respectively. For reconstituted skimmed and whole milk, maximum MCA of Rm4 and MW150 proteases were achieved at the concentrations of 10 % and 15 %, and 4 % and 3.36 %, respectively.