An elastase-like enzyme in the oocytes of Arbacia punctulata

An elastase-like enzyme was demonstrated in the unfertilized eggs of Arbacia punctulata. The enzyme was discovered in the fertilization product of A. punctulata, but was also found to be present in the seawater surrounding unfertilized eggs. Isolation of the elastase-like enzyme was accomplished by preparation of a 100,000g supernatant from a homogenization of unfertilized eggs. Its presence and specificity were determined by assay using a synthetic peptide substrate. The elastase-like activity was nondialyzable, heat labile, and unstable at pH 4. The enzyme was inhibited by antipain, elastatinal, and DFP, but not by leupeptin or soybean trypsin inhibitor. Eggs were fertilized and developed normally in the presence of 1.0 mM elastatinal. Trypsin-like and chymotrypsin-like enzymes were also found in the seawater surrounding fertilized eggs. The trypsin-like enzyme was isolated from this source and characterized by inhibitor profile.