Proteolytic Activity of Some Milk-Clotting Enzymes on κ-Casein

Abstract

Proteolytic activity of some milkclotting enzymes [calf rennet (chymosin), Mucor miehei rennet, and Cryphonectria parasitica rennet] on lCcasein was detennined with reversephase HPLC. All enzymes were standardized to the same milkdotting activity and incubated with lC-casein at 37"C for 1, 5, 15, 30, and 60 min. Protein hydrolysis was stopped by addition of 10-5 M pepstatin in 8 M urea. Chromatograms of hydrolysis products revealed that the enzymes hydrolyzed lC-casein differently. Chymosin hydrolysis was limited to formation of lC-macropeptide and para-lC-casein; the microbial rennets, particularly that from M. miehei, effected extensive nonspecific hydrolysis of both lC-casein and para-lC-casein. (