Isolation and characterization of a lectin from tulip bulbs, Tulipa gesneriana

A lectin, which agglutinated specifically the yeast cells of the Saccharomyces genus, was isolated from tulip bulbs (Tulipa gesneriana) using affinity chromatography on mannan-Sepharose 4B. Its relative molecular mass was determined by gel filtration to be approximately 67,000. On polyacrylamide gel electrophoresis in sodium dodecyl sulfate, a relative molecular mass of 17,000 was obtained, suggesting that the lectin is a tetramer. Binding studies performed with iodinated lectin indicated that Saccharomyces cerevisiae cells contained approximately 5.7 X 10(6) binding sites per cell, whereas little binding was observed with yeasts other than the Saccharomyces genus, bacteria and animal erythrocytes. D-Mannose, D-mannose 6-phosphate, L-fucose and L-fucosylamine were potent inhibitors of the lectin binding to S. cerevisiae cells, while, D-glucose, D-galactose and D-mannosamine were inactive, indicating that hydroxyl group at C-2 of D-mannose was essential for the lectin binding. Furthermore, inhibition experiments, using various manno-oligosaccharides, suggested that the lectin recognized (1----6)-linked manno-oligosaccharide units larger than mannobiose.