Evaluation of Gelatinolytic and Collagenolytic Activity of Fasciola hepatica Recombinant Cathepsin-L1

Background: Cysteine proteases of the liver fluke, Fasciola hepatica, participate in catabolism of proteins, migration of the fluke through host tissues and combat host immune system. Objectives: In this study, we evaluated proteolytic activity of F. hepatica recombinant cathepsin L1 (rCL1) against gelatin and collagen as common substrates. Material and Methods: The coding sequences of F. hepatica CL1 were cloned and expressed in Escherichia coli, in our previous study. The rCL1 was purified by nickel affinity chromatography with a HisTrap Column. The protein concentrations of the purified fractions were determined by Bradford assay. Rat collagen type-1 was treated with distinct amounts of rCL1 at 37 °C, overnight, and the byproduct was analyzed by SDS-PAGE. Furthermore, we used bovine skin gelatin as zymography substrate to evaluate the gelatinolytic activity of the purified rCL1. Results: Recombinant CL1 was capable to digest intact type-1 collagen within 24 h and the gelatinlytic activity of rCL1 was visible at approximately 37 kDa region, with optimal activity at acidified conditions (pH 4). Conclusion: Findings provide a possible mechanism by which a major secretory molecule of F. hepatica could be involved in parasite survival as well as its pathogenesis.