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

The effect of salts on hatching enzyme and protease from the embryo of the sea urchin, Hemicentrotus 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 CaCL , NaCI and KCI, while inhibited by MgCI . Protease activity was maximal at about 0.25 M NaCI. KCI, NH , CI and LiCI. Maximal activity of hatching enzyme was obtained at 0.5 M NaCl, KCI and NH CI, while activity was inhibited by any concentration of LiC1. Among monovalcnt cations, the order of activation was NaCI, KCI > NH Cl. The activity of hatching enzyme was stabilized by dialysis against 1 M NaCI or KCI in the presence of CaCl. , but was rapidly lost by dialysis against lower concentrations of salts. Reactivation of hatching enzyme was not achieved by redialysis against I M NaCI. On the other hand, protease was reactivated by I M NaCI or KCI. From these results, hatching enzyme of the sea urchin may be called a moderate halophilic enzyme. It was assumed that at least two enzymes exist in the crude enzyme preparation and that they may have different functions.