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

The breakdown of as -caseins and ~-caseins (in the form of as -caseins, the form of ~-caseins, and the form of a mixture of as- and ~-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, as- and ~-caseins were degraded up to 46 and 76 %, respectively, by 10 h of hydrolysis. In separated form, as-caseins reached a leveI of degradationup to 67 %while ~-caseins were quickly and extensively degraded up to 76 %. Ingeneral, ~-caseins seemed to be more susceptible to proteolysis than as-caseins