This 86,000 molecular weight glycoprotein contains two chains of 40,000 and 46,000 daltons joined by disulfide bonds. This lectin is free of a reported 32,000 molecular weight contaminant protein. The carbohydrate binding site recognizes (b-1,4) linked N-acetylglucosamine oligomers, preferring chitobiose or chitotriose over a single N-acetylglucosamine residue. This lectin binds well in the acidic pH range but its affinity decreases above pH 8.0. DSL is mitogenic toward human peripheral lymphocytes and its potency has been reported to increase as the lectin aggregates to larger molecular weight species. Datura lectin also binds well to N-acetyllactosamine and oligomers containing repeating N-acetyllactosamine sequences. A branched pentasaccharide including two N-acetyllactosamine disaccharides linked to mannose (b-1,6) and (b-1,2) was reported to be the most potent inhibitor of agglutination. Carcinoembryonic antigen, capsular polysaccharides and many glycoproteins have binding sites for this lectin. |