Proteolytic activities of some milk clotting enzymes on ovine casein

Proteolytic activity of some milk clotting enzymes (calf and lamb rennets, bovine chymosin and pepsin, and proteases from Rhizomucor miehei and Crypho nectria parasitical on ovine whole casein was determined by urea-PAGE and R P-HPLC. Microbial enzymes were more proteolytic than animal enzymes when ac ting on ovine whole casein. Lamb rennet and C. parasitica protease showed t he lowest and the highest degree of proteolysis, respectively. Urea-PAGE re sults showed that all enzymes hydrolyzed ovine casein resulting in the form ation of alpha(s1)-I and beta-I as initial breakdown products of alpha(s1)- CN and beta-CN. In addition to these products, C. parasitica protease produ ced a series of degradation products with lower mobilities than beta-CN. Mi nor quantitative differences between coagulants from animal origin, but gre at quantitative and qualitative differences between microbial and animal co agulants (assessed throughout the study of the RP-HPLC peptide profiles), w ere observed. (C) 2000 Elsevier Science Ltd. All rights reserved.