CATHEPSIN-B, CATHEPSIN-D, CATHEPSIN-H AND CATHEPSIN-L ACTIVITIES IN THE PROCESSING OF DRY-CURED HAM

The activities of cathepsins B, D, H and L have been assayed at various stages in the slow processing (15 months) of dry-cured ham. Cathepsins B, H and L showed low recovered activity (5-10 % of the initial activity) at the end of the process. However, cathepsin D almost disappeared after 5-10 months. Water-soluble protein extractability decreased throughout the process while myofibrillar protein extractability was constant. There was a progressive disappearance of myosin heavy chain, myosin light chains 1 and 2, and troponins I and C, a marked increase of three breakdown products with molecular weights of about 150, 95 and 16 kDa and some minor products in the ranges 50-100 kDa and 20-45 kDa. Cathepsins B and L could be particularly active in the observed proteolysis which had a special relevance when the drying started. Actin, actinin, troponin T and tropomyosin did not seem to change.