Proteolysis of ovine caseins by cardosin A, an aspartic acid proteinase from Cynara cardunculus L.

The breakdown of α_s-caseins and β-caseins (in the form of α_s-caseins, the form of β-caseins, and the form of a mixture of α_s- and β-caseins in Na-caseinate) by cardosin A, one of the major two proteinases present in the flowers of Cynara cardunculus L., was experimentally studied via urea polyacrylamide gel electrophoresis. In Na-caseinate, α_s- and β-caseins were degraded up to 46 and 76 %, respectively, by 10 h of hydrolysis. In separated form, α_s-caseins reached a level of degradation up to 67 % while β-caseins were quickly and extensively degraded up to 76 %. In general, β-caseins seemed to be more susceptible to proteolysis than α_s-caseins.