INVESTIGATING AND EVALUATING THE PROTEASE ACTIVITY AND THE EFFECT OF pH AND TEMPERATURE ON SERINE PROTEASES AND CYSTEINE PROTEASES ACTIVITIES IN ADULT HELMINTH OF FASCIOLA HEPATICA

Fascioliasis is a zoonotic disease caused by the trematode Fasciola hepatica.
Proteases are essential for the survival of parasites. This study was conducted to evaluate the serine and
cysteine proteases of F. hepatica and also to the investigate the effect of pH and temperature on proteases
activity and their temperature stability.
Materials & Methods: Adult Fasciola were isolated from infected livers and their protein levels were
measured. The total proteolytic activity of the extract of F. hepatica was evaluated using azocasein
substrate in pH values from 2 to 12. Trypsin, chymotrypsin and cathepsin B substrates were used to
measure protease activity. We evaluated the effect of protease inhibitors, PMSF, pepsin, DTT and EDTA
on these enzymes. The estimation of optimum temperature and pH was performed within a temperature
range of 10-90 ° C and at pH levels 2-12.
Results: The optimum pH activity of trypsin and chymotrypsin were recorded at an alkaline pH and total
proteolytic activity and cathepsin B were recorded at an acidic pH. The results showed that F. hepatica
had serine and cysteine protease activity. The optimum temperature activity for trypsin and
chymotrypsin was 50 ° C. The optimum temperature activity for cathepsin B was at 30 to 40 ° C. The
temperature stability for the three proteases was up to 40 ° C.
Conclusion: The high temperature stability of F. hepatica proteases showed that they could be used as
a potential factor in biological applications such as vaccine and anti-parasitic drugs