Characterization of Boar Seminal Plasma, Vesicular Secretion and Epididymal Plasma Proteins by Gel Disc Electrophoresis and Isoelectric Focusing on Polyacrylamide

Summary. Boar seminal plasma, vesicular secretion and epididymal plasma proteins were studied by gel disc electrophoresis at pH 4·5 and 8·6 and by isoelectric focusing in tubes and on plates using ampholines of pH range 3 to 10. The number of protein bands obtained in the gel disc electrophoresis was fifteen to twenty for all the samples. A similarity between the proteins of the seminal plasma and the vesicular secretion was greater at pH 4·5 than at pH 8·6. The epididymal plasma showed a different separation picture. The better resolution of the isoelectric focusing revealed a greater number of proteins. Similar protein patterns were found for the vesicular secretion and the seminal plasma in the basic part of the pH range, where the majority of the proteins of these fluids are found. The proteins of the epididymal plasma, on the other hand, possess more neutral isoelectric points and their contribution to the seminal plasma is smaller than that of the vesicular secretion. Only a few of the epididymal plasma proteins and of the minor vesicular secretion proteins could be found in the neutral and acidic regions of the seminal plasma. This is largely the result of the dilution of these accessory secretions occurring during ejaculation. Differences in the protein pattern of the seminal plasma of various animals could be found. The importance of these differences is as yet unknown.