The purification and characterization of a cysteine protease of Fasciola gigantica adult worms.

A 26-28 kDa protease was isolated from Fasciola gigantica adult worms by a two-stage purification process of column chromatography in a Sephacryl S-200 column and affinity chromatography in an L-phenylalanine-agarose column. This protease is a cysteine (thiol) proteinase with an optimum pH of 4.5 and is not inhibited by anti F. gigantica immunoglobulin G. The enzyme was inhibited by protease inhibitors known to inhibit cysteine proteases but not by metallo-, aspartate or serine protease inhibitors. The effect of several protease inhibitors and anti-F, gigantica IgG was also assessed on the total proteolytic activity of F. gigantica. There appears to be a preponderance of cysteine protease activity in F. gigantica and there was a significant inhibition of total proteolytic activity by anti-F. gigantica IgG.