Isolation of sperm bindin from the oyster (Crassostrea gigas)

Abstract

AbstractA method was devised for isolating the insoluble content of the acrosome granule of sperm of the oyster Crassostrea gigas. The method involves the dissolution of the entire cell, except for the acrosome granule, in the detergent sodium lauroyl sarcosinate (sarcosy I). The isolated acrosome granule content is ring‐shaped and is 84% protein by weight. SDS‐polyacrylamide gel electro‐phoresis of this material yields from 1 to 4 bands of 65,000; 53,000; 43,000 and 34,000 apparent molecular weight, all of which stain with the PAS reaction indicating the material is a glycoprotein. The 65,000 molecular weight component is always present, but the presence of the other three bands varies with each preparation. The isolated acrosome granules agglutinate formaldehyde‐fixed oyster eggs. A trypsin‐generated glycopeptide digest of oyster egg surfaces inhibits the agglutinin activity of the isolated acrosome granules. We propose that the acrosomal glyco‐protein material is oyster sperm bindin which functions as the adhesive substance bonding the sperm to the egg during fertilizaion.