Heat-stable protease from the marine sponge Geodia cydonium.

A protease from the marine sponge Geodia cydonium was purified from an aqueous extract by gel filtration and anion-exchange chromatography. A 200-kDa proteolytically active band was obtained when the enzyme was analyzed in gelatin-copolymerized zymograms. The enzyme was also able to degrade casein, bovine collagen, and the synthetic substrate alpha-N-benzoyl-D-arginine p-nitroanilide (BAPNA). Optimal conditions for proteolytic activity were achieved in the presence of 10 mM CaCl2 and within the pH range 7.0 to 8.5. The protease showed an extraordinary heat resistance. The enzyme activity was inhibited by phenylmethylsulphonyl fluoride (PMSF) and N-tosyl-lysine chloromethyl ketone (TLCK), suggesting that the enzyme belongs to the group of serine-type proteases. We propose that the protease is involved in sponge collagen catabolism.