The heparin-binding activity of bull seminal plasma proteinswas inhibited by D-fructose, D-glucose, inulin and glycogen. The heparin-binding activity of epididymal sperm was inhibited by D-fructose. The results of the binding studies were confirmed by affinity chromatography on immobilized heparin followed by elution with monosaccharides. Proteins eluted with D-fructose were analyzed by N-terminal amino acid sequence. RNAase dimer, PDC-109 and metalloproteinase inhibitor were identified.