Glycosyltransferase probes

Glycosyltransferases catalyze the transfer of a monosaccharide from an activated sugar nucleotide donor to a specific acceptor such as monosaccharides, oligosaccharides, lipids, or amino acid residues. The chapter outlines various methods and presents examples applicable to the use of virtually any soluble or membrane-bound glycosyltransferase as a probe of oligosaccharide structure. An advantage of using glycosyltransferases as surface probes is that they selectively detect accessible substrates that may be important in extracellular interactions with other cells or ligands. Therefore, the exogenous resialylation of these cells appears to be efficient, suggesting that enzyme specificity and not steric hindrance is the major factor in determining the extent of reglycosylation. Many of the known glycosyltransferases are membrane-bound enzymes that must be purified using nonionic detergents. However, to use these transferases as probes of living cells, it is necessary to remove these detergents.