A PROTEASE FROM THE MARINE SPONGE CALLYSPONGIA-SCHULZI

Aqueous extracts of 25 marine sponge species (from coral reefs of Papu a New Guinea) were screened for proteolytic activity. Only one sponge, Callyspongia schulzi, showed remarkable activity. A protease hydrolyz ing casein as well as the synthetic substrate ct N-benzoyl-L-arginine ethyl ester was isolated from the sponge extract by gel filtration, io n-exchange and HPLC absorption chromatography. The enzyme was homogeno us in SDS-PAGE exhibiting an apparent molecular weight of 80 kDa. Its pH optimum was in the range of 9-11, it was remarkably heat-stable and was not inhibited by phenylmethane sulfonylfluoride, soybean trypsin inhibitor, aprotinin or alpha(1)-antitrypsin, but by EDTA and 1,10-phe nanthroline suggesting properties of a metalloprotease. The protease h ydrolyzed the oxidized insulin B-chain between Arg(22)-Gly(23) and Lys (29)-Ala(30), similar to trypsin.