SPERM-ACTIVATING PROTEINS FROM UNFERTILIZED EGGS OF THE PACIFIC HERRING, CLUPEA-PALLASII

Ripe unfertilized eggs of the Pacific herring, Clupea pallasii, releas e sperm-activating proteins into seawater at the time of fertilization . Five species of herring sperm-activating proteins (HSAP) with differ ent pl values (4.8, 4.9, 5.0, 5.1 and 5.4) were purified from the egg- conditioned medium by gel filtration and isoelectric focusing. Molecul ar mass of the HSAP (pl = 5.1), the major species of the five HSAP, wa s determined to be 8.1 kDa by mass spectrometry. Molecular weights of all of the HSAP were estimated to be 7700 by sodium dodecyl sulfate po lyacrylamide gel electrophoresis (SDS-PAGE). The first 20 amino acid s equences from N-terminal ends of three HSAP (pl = 4.9, 5.0 and 5.1) we re almost identical, suggesting that the HSAP have similar structures.