Abstract:

In this study, 0.58 mg of purified enzyme was prepared from acidification and subsequent extraction of fresh
bovine pancreas homogenate followed by purification through salting out and column chromatography. The purification
fold was 530.54. The purified enzyme had two subunits with molecular weights of 18.9 and 29.1 kD, respectively on SDSpolyacrylamide
gel electrophoresis (SDS-PAGE). The optimum reaction temperature for bovine pancreas cathepsin L was
50 ℃, and the optimum pH was 6.5. Its enzyme activity was efficiently activated by dithiothreitol (DTT) and L-cysteine
(L-Cys), while it could be completely inhibited by 10 μmol/L E-64 and evidently suppressed by 1 mmol/L Zn2+. The purified
enzyme could hydrolyze Z-Phe-Arg-MCA with a Km value of 3.52 μmol/L.

Key words: cathepsin L, bovine pancreas, purification, enzymatic characterization