Serine-like proteolytic enzymes from common carp Cyprinus carpio L. seminal plasma are able to degrade sperm proteins.

The application of zymography, with sperm proteins as a substrate, allowed for the first time the visualisation of two serine proteinases with a molecular weight of 76 and 163kDa from common carp Cyprinus carpio L. seminal plasma. Twenty four hours of incubation in a development solution with a pH of 7.5 and incubation at 37°C were the best conditions for the visualisation of serine proteinase; however, proteolysis was also observed at 4°C. Our results indicate that serine proteinase from common carp seminal plasma with a molecular weight of 76 and 163kDa may be involved in the degradative mechanism of sperm proteins. This mechanism may be responsible for the removal of damaged sperms by the digestion of native sperm proteins.