SEASONAL-CHANGES AND PRELIMINARY CHARACTERIZATION OF CATHEPSIN-D LIKEACTIVITY IN SARDINE (SARDINA-PILCHARDUS) MUSCLE

The seasonal changes of cathepsin D-like activity in white and dark mu scle of sardine were followed and maximum activity was found in April and October, which could be related to the spawning period of this spe cies. Higher catheptic activity was measured in dark muscle and female s. The crude extract of this muscle enzyme had an optimum pH and tempe rature of 3.2 and 55 degrees C, respectively, and the activity was str ongly inhibited by low levels of NaCl (6%). The thermal stability was lower at pH 3.2 than at FH 6.5 and the enzyme was stable in the pH ran ge 3-4.5. The activity of this protease was detected during the ripeni ng process of salted sardine which suggests its participation in this process.