THE VEGETABLE RENNET OF CYNARA-CARDUNCULUS L CONTAINS 2 PROTEINASES WITH CHYMOSIN AND PEPSIN-LIKE SPECIFICITIES

The flowers of cardoon (genus Cynara) are traditionally used in Portug al for cheese making. In this work the vegetable rennet of the species Cynara cardunculus L. was characterized in terms of enzymic compositi on and proteolytic specificity of its proteinases (cardosin A and card osin B). Cardosin A was found to cleave insulin B chain at the bonds L eu15-Tyr16, Leu17-Val18 and Phe25-Tyr26. In addition to the bonds ment ioned cardosin B cleaves also Glu13-Ala14, Ala14-Leu15 and Phe24-Phe25 indicating that it has a broader specificity. The kinetic parameters for the hydrolysis of the synthetic peptide Leu-Ser-Phe(NO2)-Nle-Ala-L eu-oMe were also determined and compared to those of chymosin and peps in. The results obtained indicate that in terms of specificity and kin etic parameters cardosin A is similar to chymosin whereas cardosin B i s similar to pepsin. It appears therefore that the enzyme composition of cardoon rennet closely resembles that of calf rennet.