EVIDENCE FOR THE PRESENCE OF AN ACID PROTEASE AND PROTEASE INHIBITORS IN DORMANT EMBRYOS OF ARTEMIA-SALINA

Proteolytic activity has been implicated in several key processes in early development. In an attempt to correlate proteolytic activity with developmental events, a study of the protease(s) in undeveloped cysts of Artemia salina was initiated using 2,4,6-trinitrobenzenesulfonic acid to determine the release of amino groups upon protein hydrolysis. The versatility and sensitivity of this reagent made it possible to detect and characterize the proteolytic activity in small quantities of cysts of the brine shrimp. A protease with a molecular weight of 84,000, a pH optimum of 3.6, and a temperature optimum of 45°C was partially purified from Artemia cysts using ion-exchange chromatography and gel filtration. In addition, two acid protease inhibitors, one dialyzable and one nondialyzable, were found in crude extracts of the cysts. The latter was partially purified and found to have a molecular weight of between 10,000 and 20,000. The activity of the acid protease is not dependent on CaCl2 or EDTA, but CaCl2 in the reaction mixture increases the rate of inactivation of the nondialyzable protease inhibitor. The inhibitors may complex with the acid protease in the embryo and control its activity during development. © 1979.