X. Zuo et Ptk. Woo, CHARACTERIZATION OF PURIFIED METALLOPROTEASE AND CYSTEINE PROTEASES FROM THE PATHOGENIC HEMOFLAGELLATE CRYPTOBIA-SALMOSITICA KATZ 1951, Parasitology research, 84(6), 1998, pp. 492-498
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.