Partial Purification of the Sperm-binding Factor from the Egg of the Sea Urchin, Anthocidaris Crassispina, Followed by an Immunological Method: (sperm-binding factor/sea urchin egg/Fab fragments/neutralizing activity/purification).

Univalent antibody (Fab fragments) against sperm-binding factor inhibits the fertilization of eggs species-specifically. The sperm-binding factor was partially purified from unfertilized eggs of the sea urchin Anthocidaris crassispina by monitoring its neutralizing effect on fertilization inhibiting Fab fragments. It formed two species-specific precipitin lines by the double-immunodiffusion test and gave three main bands of protein with apparent molecular weights of 80,000, 87,000 and 225,000, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Carbohydrate was detected in the first and third of these protein bands.