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

Abstract

Electrophoretic analysis of the action of two commercial enzymes, Neutrase 0·5 and MKC Fungal Protease, on whole casein and αs-, β- and κ-caseins from cows' and ewes' milk showed that Neutrase 0·5 chiefly degraded β-casein, giving rise to peptides soluble at pH 4·6 detectable by PAGE. In contrast, although MKC Fungal Protease caused intense hydrolysis of bovine β-casein, in ovine casein it resulted in more active degradation of αs- than β-casein. The latter enzyme did not produce peptides soluble at pH 4·6 detectable by PAGE. Both enzymes degraded κ-casein, yielding a breakdown product that exhibited an electrophoretic mobility similar to that of the breakdown product produced by the action of commercial rennet.