Protamines and related proteins from spermatozoa of molluscs. Characterization and molecular weight determination by gel electrophoresis.

The spermatozoa of most species of molluscs contain a mixture of proteins with compositions related to those of histones and protamines. The various components present in the spermatozoa of Cryptochiton stellerii, Donax trunculus, Mactra corallina and Gibbula divaricata have been isolated and characterized. The results obtained, taken together with those previously found (Subirana, J.A., Cozcolluela, C., Palau, J. and Unzeta, M. (1973) biochim. Biophys. Acta 317, 364--379), show that in all the molluscs studied one or more arginine-rich components are present. The molecular weight of these proteins varies vary much in different species and is usually much greater than in conventional fish protamines. Conventional histones, as well as lysine-rich proteins of low molecular weight, have also been found in ripe spermatozoa of several species. The molecular weights have been estimated by gel electrophoresis, using polymerized iridine as a standard.