Separation of the fertilization membrane in Urechis and sea urchin eggs as a phenomenon caused by breakage of hydrogen bonds : IV. Denaturing action of proteolytic enzymes

Abstract

Summary When sea urchin, starfish and Urechis eggs are immersed in sea water containing activated papain or chymopapain, they elevate a fertilization membrane and formation of the hyaline layer as well as nuclear activation is brought about. The enzymes cause such membrane elevation in sea urchin eggs in isotonic solutions of sodium chloride and of potassium chloride. The elevated membrane often retracts to the egg surface and then separates again. The first elevation of the membrane is thought to be brought about by the breakage of hydrogen bonds between the vitelline and plasma membranes and of those within the vitelline membrane, owing to the denaturing action of the proteolytic enzyme. The second elevation is caused by the hydrolytic action of the enzyme, which causes extrusion of the cortical granules. The membrane is elevated owing to an osmotically active substance which releases these granules. Hemicentrotus eggs only respond to activated bromeline. In addition to papain and chymopapain, trypsin and chymotrypsin are effective in elevating the membrane of Urechis and starfish eggs.