PURIFICATION AND CHARACTERIZATION OF SEVERAL DIGESTIVE PROTEASES FROMTHE BLUE ABALONE, HALIOTIS FULGENS

Several proteases were found in an aqueous extract from the hepatopanc reas of blue abalone. Four, called PH1, PH2, PH3 and PH4, were purifie d by ammonium sulfate precipitation, low pressure DEAE-Sepharose chrom atography and anion exchange HPLC. All these proteases were active on protein substrates (casein and hide powder azure); they showed differe nt activities with synthetic substrates and were inhibited by differen t compounds. PHI, PH2 and PH3 seemed to be serine-like proteases (PHI, chymotrypsin-like; PH2 and PH3, trypsin-like) while protease PH4 had carboxypeptidase behavior. The purified enzymes showed single bands in SDS-PAGE and IEF minigels showing relative molecular masses of 28,100 , 29,500, 32,000 and 30,000, and isoelectric points of 6.3, 3.6, 4.0 a nd 3.8, respectively. PH1, PH2 and PH3 have common features in their a mino acid contents. These enzymes possess different secondary structur es as judged from their circular dichroism spectra. (C) 1998 Elsevier Science B.V.