Purification of a 44 kilodalton protease which mediates the ecdysis of infective Haemonchus contortus larvae.

We have characterized and purified a parasite protease which mediates the ecdysis of Haemonchus contortus, and at least several other ruminant trichostrongyles. The protease, with an apparent approximate molecular weight of 44,000, is a zinc metalloprotein which hydrolyzes several large protein substrates in in vitro assays. In vivo and in biological assays on isolated second molt cuticles this protease hydrolyzes a specific circular region of the second stage cuticle which results in removal of a cuticular cap, providing a rapid and synchronous method for the escape of infective larvae during the transition from free-living to parasitic environments.