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

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Abstract
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 67000. On polyacrylamide gel electrophoresis in sodium dodecyl sulfate, a relative molecular mass of 17000 was obtained, suggesting that the lectin is a tetramer. Binding studies performed with iodinated lectin indicated that Saccharomyces cerevisiae cells contained approximately 5.7 × 106 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-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.