Haemonchus contortus: characterization and purification of excretory/secretory protease(s).

The activity of protease(s) has been examined separately in excretory/secretory (E/S) products from male and female Haemonchus contortus (Nematoda: Trichostrongylidae). The E/S proteolytic activity indicated the presence of preabsorptive digestion of host blood and/or tissues. Protease activity was optimum at 37 degrees C, pH 8.5 and 8.0 mg casein. These protease(s) were purified to 32.16- and 88.80-folds from male and female E/S products, respectively, by sequential purification with saturated ammonium sulphate followed by ion-exchange chromatography. The purification study revealed the presence of isomeric forms of protease(s) in the E/S products of H. contortus.