Purification and characterization of trypsin-like enzyme from sea urchin eggs: substrate specificity and physiological role.

A trypsin-like enzyme has been purified to homogeneity from eggs of the sea urchin, Strongylocentrotus intermedius. The purified enzyme efficiently hydrolyzed Z-Phe-Arg-4- methylcoumaryl -7-amide (MCA) and Pro-Phe-Arg-MCA among 12 peptidyl-Arg (or Lys)- MCAs . The substrate specificity of the enzyme was closely similar to that of the enzyme activity in the egg cortical granule exudate. Among various peptidyl-argininal (Arg-H) derivatives, Z-Phe-Arg-H and Z-Phe-Leu-Arg-H showed the strongest inhibition against both the activity of the purified enzyme and the elevation of vitelline coat. Thus, the trypsin-like enzyme of sea urchin possesses a narrow substrate specificity and participates at least in the elevation of vitelline coat during fertilization.