SALT-DEPENDENT PROPERTIES OF HATCHING ENZYME FROM EMBRYOS OF THE SEA URCHIN, HEMICENTROTUS PULCHERRIMUS

Abstract

The effect of salts on hatching enzyme and protease from the embryo of the sea urchin, H. pulcherrimus, was investigated. The culture medium containing hatching enzyme secreted from the hatched blastula was dialyzed against Tris-HCl (pH 8.0) with or without salts. Both hatching enzyme and protease were activated and stabilized by CaCl2, NaCl and KCl, while inhibited by MgCl2. Protease activity was maximal at about 0.25 M NaCl, KCl, NH4Cl and LiCl. Maximal activity of hatching enzyme was obtained at 0.5 M NaCl, KCl and NH4Cl, while activity was inhibited by any concentration of LiCl. Among monovalent cations, the order of activation was NaCl, KCl > NH4Cl. The activity of hatching enzyme was stabilized by dialysis against 1 M NaCl or KCl in the presence of CaCl2, but was rapidly lost by dialysis against lower concentrations of salts. Reactivation of hatching enzyme was not achieved by redialysis against 1 M NaCl. Protease was reactivated by 1 M NaCl or KCl. From these results, hatching enzyme of the sea urchin may be called a moderate halophilic enzyme. It was assumed that at least 2 enzymes exist in the crude enzyme preparation and that they may have different functions.