Changes in the sialylglycoconjugate distribution on the human sperm surface during in-vitro capacitation: partial purification of a 20 kDa sialylglycoprotein of capacitated spermatozoa.

Changes in the distribution of sialylglycoconjugates on the surface of uncapacitated and in-vitro capacitated human spermatozoa were studied by means of two sialic acid specific lectins (Maackia amurensis agglutinin and Sambucus nigra agglutinin). On the uncapacitated sperm surface, sialylglycoconjugates were found to be localized from the post-acrosomal region of the sperm head to the tail middle piece, whereas after in-vitro capacitation these molecules were only found in a small area of the post-acrosomal region. The surface of capacitated human spermatozoa was also investigated by specifically radiolabelling its terminal sialic acid residues. A 20 kDa glycoprotein, which was partially purified by anion-exchange chromatography, was the main component of the sialylglycoconjugate pattern after in-vitro capacitation.