Hydrolysis of β-casein by gastric proteases

I. Comparison of proteolytic action of bovine chymosin and pepsin A


J. P. Pélissier Station de Recherches Laitières INRA 78350 Jouy-en-Josas France


Hydrolysis of βA2-casein by bovine chymosin and pepsin A was performed in order to compare the hydrolysis of the two enzymes on this protein. Different conditions have been tested: pH 5.5 for 116 h and pH 3.5 for 7h[E/S = 1/100 (w/w)] for chymosin. pH 3.0 for 24 h [E/S = 1/1000 (w/w)] for pepsin A. Under these conditions 17 peptides were obtained after the action of chymosin and 23 after the action of pepsin A. They corresponded respectively to the cleavage of 14 and 15 peptide bonds for chymosin and pepsin A. However, six of the peptide bonds were only hydrolyzed by chymosin and seven other bonds only by pepsin A. Our results showed a preferential splitting at the Leu-X, Ser-X, and Trp-X bonds for chymosin and Leu-X, Met-X, and Thr-X, for pepsin A. Some of the identified peptides contained sequences with possible physiological roles.