SACCHARIDE-BINDING PROPERTIES OF BOAR AQN SPERMADHESINS AND DQH SPERMSURFACE PROTEIN

Heparin-binding proteins BHB 2-BHB 5 were purified from boar seminal p lasma by affinity chromatography on a heparin-polyacrylamide column an d reversed phase HPLC. Three of the proteins, BHB 3-BHB 5, were found to be identical to spermadhesins AQN 1-AQN 3 isolated from boar sperma tozoa, The lectin-like properties of the isolated proteins BHB 2-BHB 5 were studied using double-diffusion in agarose gel, enzyme-linked bin ding assay, and inhibition assays of erythroagglutinating activity. It was found that proteins BHB 3-BHB 5 (spermadhesins AQN 1-AQN 3) inter acted with glycoproteins containing O-glycosidically bound oligosaccha ride chains, but not with those containing only N-linked carbohydrate chains. The strongest interaction was observed between BHB 3 (AQN 1) a nd desialyzed bovine submaxillary gland mucin, the glycoprotein contai ning only O-glycosidically linked saccharides, No interaction of BHB 3 -BHB 5 proteins with simple saccharides, their derivatives or acidic p olysaccharides was observed, Both the hemagglutinating activity and sa ccharide-binding properties of BHB 2 protein were quite different. Agg lutinating activity of human erythrocytes by BHB 2 protein was signifi cantly higher than that by BHB 3-BHB 5 proteins (AQN spermadhesins). I n contrast to AQN spermadhesins, BHB 2 protein (DQH sperm surface prot ein) interacted strongly with acidic polysaccharides and sialyzed glyc oproteins, but no binding of desialyzed glycoproteins as well as N-ace tyl-alpha-D-galactosaminyl-O-serine, simple monosaccharides and amino sugars was observed.