CHARACTERIZATION OF PURIFIED METALLOPROTEASE AND CYSTEINE PROTEASES FROM THE PATHOGENIC HEMOFLAGELLATE CRYPTOBIA-SALMOSITICA KATZ 1951

The purified metalloprotease and the partially purified cysteine prote ase from pathogenic Cryptobia salmositica were characterized. Using ha emoglobin gel electrophoresis, we detected five enzymatic bands in cru de parasite lysate; one protease (200 kDa) yielded a metalloprotease b and and other four, cysteine protease bands (97, 70, 66 and 49 kDa). B oth the metalloprotease and the cysteine protease had high levels of p roteolytic activity against azocasein, haemoglobin and fibrinogen. The metalloprotease had high levels of activity against azocoll and gelat in but a low degree of activity against albumin. In contrast, the cyst eine protease had extensive activity against albumin but low levels of activity against azocoll and gelatin. The metallo- and cysteine prote ases had no activity against Pz-peptide, a specific substrate for bact erial collagenase. The optimal pH for the metalloprotease and the cyst eine protease was 7.0 and 5.0, respectively. The metalloprotease was i nhibited by metal-chelating agents and excess of zinc ions but was act ivated by calcium ions. The cysteine protease was inhibited by thiol-b locking agents. The natural antiprotease alpha 2-macroglobulin, but no t alpha 1-protease inhibitor, inhibited the activity of both proteases from C. salmositica. The optimal in vitro temperature for the purifie d metalloprotease was 30 degrees C.