Parameters Affecting Cell Binding to Lectin Beads in Carbohydrate‐Based Drug Development

Abstract

Using a model system of washed yeast (Saccharomyces cerevisiae) that possess mannose‐rich cell surfaces and washed concanavalin A derivatized agarose beads that preferentially bind to glycans containing mannose/glucose residues, we tested 4 concentrations of alpha methyl mannose and the same 4 concentrations of D‐melezitose (0.025 mM – 25 mM) and a 50/50 mixture of these 2 sugars at the same final concentrations, over a 30 minute time course, assaying how much yeast remained bound to the beads at 10 minute intervals with and without sugar at each sugar concentration tested. In 15,379 replicate experiments, averaging about 300 trials for each sugar at each time tested, alpha methyl mannose and D‐melezitose caused dissociation of yeast from the Con A beads in a concentration dependent manner with an almost linear time course with little dissociation occurring immediately and incrementally increased dissociation occurring after 10,20 and 30 minutes. The highest sugar concentration (25 mM) tested here was most effective in causing dissociation and the 50/50 mixture of sugars was less effective than the single sugars in causing dissociation at the lower concentrations (less than 25 mM). The results suggest that careful attention should be paid to sugar concentration and incubation times in experiments using lectin derivatized beads in molecular purification protocols and in development of carbohydrate‐based drugs and diagnostic tests (Supported by NIH NIGMS SCORE (S06‐48680, NIH MBRS RISE, NIH MARC and the Joseph Drown Foundation).