Enzymatic hydrolysis of milk proteins brought about by an aspartic peptidase from Silybum marianum flowers

VAIRO CAVALLI, S.; SILVA, S.; CIMINO, C.; MALCATA, F.X.; PRIOLO, N.

Pinamar

Congreso; X Congress of the Panamerican Association for Biochemistry and Molecular Biology (PABMB), XLI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB), XX Annual Meeting of the Argentine Society for Neurochemistry (SAN); 2005

Panamerican Association for Biochemistry and Molecular Biology (PABMB)

The flowers of different species of cardoon (Asteraceae) have been characterized once they are a rich source of aspartic peptidases with milk clotting activity, such as Cynara cardunculus L. flowers which are used in traditional cheesemaking in the Iberian Penynsula. This study was aimed at characterizing the enzymatic action of the aspartic peptidase presents in flowers of Silybum marianum (L.) Gaertn. (Asteraceae) in terms of the degradation of caseins. The proteolytic activities toward Na-caseinates from caprine and ovine milks were studied in a comparative fashion using urea-PAGE, tricine-SDS-PAGE, densitogram analysis, electroblotting and sequencing. Caprine ás1- and â- caseins were degraded up to 68%, and 40% respectively during 24 hours of incubation. Only one important and well defined band of 14,4 kDa, a fragment of b-casein, was observed after 12 hours of hydrolysis. On the other hand, after 24 hours of incubation, the ovine as- and â-caseins were degraded up to 76%, and 19 % respectively. In what concerns to specificity of the proteolytic activity towards ovine caseinate the major cleavage site was Leu99-Arg100 in ás1-casein.