Fluorometric assay of binding specificity of plant lectins to yeast cells by biotin-avidin system and its application to the classification of yeast cells.

A fluorometric assay of lectin binding to yeast cells is reported. The relative amount of biotinylated lectins bound to the yeast cells was estimated by enzyme activity using 4-methylumbelliferyl-beta-D-galactoside as a substrate for the lectin-bound beta-galactosidase through biotin-avidin interaction. Binding properties of 4 mannose-specific and 3 glucose/mannose-specific lectins to 22 different species of yeast cells were studied. The binding reaction of biotinylated lectins to the yeast cells was rapid and became constant within 10 min. Each lectin showed its characteristic binding specificity to each yeast species. The relative fluorescent intensities observed for 4-methylumbelliferone released by the action of bound beta-galactosidase were good indicators for the classification of yeast cells in quantitative base. We found that the yeast cells of the Saccharomyces genus can be classified into three groups, and those of Pichia were grouped into two groups. The present method can examine many samples simultaneously and be completed within 3 h.