This lectin appears to bind only O-glycosidically linked oligosaccharides, preferring the structure galactosyl (β-1,3) N-acetylgalactosamine. This structure (the T-antigen) is the oligosaccharide to which peanut agglutinin (PNA) binds. However, unlike PNA, Jacalin will bind a mono- or disialylated form of this structure. This lectin has been used to purify human IgA. The specificity of this lectin also affords the opportunity to localize or isolate glycoproteins with O-glycosidically linked oligosaccharide side chains. Biotinylated Jacalin has an appropriate number of biotins bound to provide the optimum staining characteristics for this lectin. This conjugate is supplied essentially free of unconjugated biotins and is preserved with sodium sodium azide.