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

The breakdown of alpha(s)-caseins and beta-caseins (in the form of alpha(s)-caseins, the form of beta-caseins, and the form of a mixture of alpha(s)- and beta-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, alpha(s)- and beta-caseins were degraded up to 46 and 76 %, respectively, by 10 h of hydrolysis. In separated form, alpha(s)-caseins reached a level of degradation up to 67 % while beta-caseins were quickly and extensively degraded up to 76 %. In general, beta-caseins seemed to be more susceptible to proteolysis than alpha(s)-caseins. (C) Inra/Elsevier, Paris.