THE EFFECTS OF CA2-URCHIN EMBRYO( AND MG2+ ON THE MAJOR GELATINASE ACTIVITIES PRESENT IN THE SEA)

We have examined the effects of Ca2+ and Mg2+ on the activities of the two most prominent gelatinases present in the developing sea urchin e mbryo. The EDTA-inhibited 41 kDa gelatinase was variously reactivated by concentrations of Mg2+ at or below 15 mM while the EDTA-inhibited 8 7 kDa gelatinase could not be reactivated by Mg2+. Magnesium partially inhibited the activities of both gelatinases and Ca2+ was protective against these inhibitory effects. In competition studies Mg2+ was show n to compete with Ca2+ for binding to the gelatinase. These results de monstrate competition between Ca2+ and Mg2+ for binding to and regulat ing the activities of these gelatinases in a marine environment which contains 10 mM Ca2+ and 50 mM Mg2+. (C) 1998 Academic Press.