PURIFICATION AND PARTIAL CHARACTERIZATION OF CHYMOTRYPSIN-LIKE PROTEASES FROM THE DIGESTIVE GLAND OF THE SCALLOP PECTEN-MAXIMUS

Three variants of a chymotrypsin-like protease were purified from scal lop digestive glands successively by ion-exchange, gel filtration and high-performance liquid chromatographies. Enzyme activity was detected using succinyl-Ala-Ala-Pro-Phe-p-nitroanilide as a specific synthetic substrate for chymotrypsin, This proteinase was inhibited by chymosta tin, diisopropylfluorophosphate and phenylmethylsulfonyl fluoride, Est imated molecular mass of the purified enzyme is around 32 kDa. These i soenzymes exhibit very low activities in hydrolyzing small synthetic s pecific substrates used for trypsic, elastolytic and collagenolytic me asurements and referred mainly to a chymotrypsin-like proteinase, Very few differences were measured concerning pH profiles among the three isoenzymes. Stability is higher at low temperature for two variants. A n N-terminal analysis was performed on one variant (B) among the three isoenzymes. The alignment of the N-terminal amino acid sequence indic ates some homologies with abalone chymotrypsin-like protein and arthro pod chymotrypsin proteases as well as with vertebrate serine protease counterparts (trypsin, chymotrypsin and elastase).