Strategies for the Chemoenzymatic Synthesis of Deoxysugar Nucleotides:  Substrate Binding versus Catalysis

Sugar nucleotidyltransferases, also known as sugar pyrophosphorylases, catalyze the formation of a phosphate linkage to produce sugars activated for use by Leloir pathway glycosyltransferases and are subjects of protein engineering for chemoenzymatic synthesis strategies. Herein we present evidence that differences in substrate binding affinity do not primarily account for substantial contrasts in deoxysugar nucleotide product yields with this class of enzymes. Prokaryotic and eukaryotic glucose-1-phosphate uridylyltransferases (EC 2.7.7.9) can exercise kinetic discrimination in choosing carbohydrates of comparable binding affinity for catalytic turnover. These findings have implications for the in vivo and in vitro function and use of these enzymes.