Proteolysis of alpha(s)-casein as a marker of Grana Padano cheese ripening

Since casein proteolysis has a critical role in defining the typical charac teristics of Grana Padano cheese, we evaluated the hydrolysis of alpha (s)- casein during the ripening process. Thanks to the high specificity of the a nti-alpha (s)(alpha (s1) + alpha (s2))-casein monoclonal antibody and amino acid sequence determination, it was possible to identify three main alpha (s)-casein-derived polypeptides in cheese: alpha (a), alpha (b), and alpha (c). Their production by the three enzymes most involved in cheese proteoly sis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro di gestions. Data showed that alpha (a) was released in cheese mainly by the c hymosin attack, while alpha (b) and alpha (c) were due to the action of pla smin. A significant correlation between the abundance of some polypeptides and ripening process was shown.