Proteolytic activity of two commercial proteinases from Aspergillus oryzae and Bacillus subtilis on ovine and bovine caseins

Electrophoretic analysis of the action of two commercial enzymes, Neutrase 0.5 and MKC Fungal Protease, on whole casein and alpha s-, beta- and kappa-caseins from cows' and ewes' milk showed that Neutrase 0.5 chiefly degraded beta-casein, giving rise to peptides soluble at pH 4.6 detectable by PAGE. In contrast, although MKC Fungal Protease caused intense hydrolysis of bovine beta-casein, in ovine casein it resulted in more active degradation of alpha s- than beta-casein. The latter enzyme did not produce peptides soluble at pH 4.6 detectable by PAGE. Both enzymes degraded kappa-casein, yielding a breakdown product that exhibited an electrophoretic mobility similar to that of the breakdown product produced by the action of commercial rennet.