Large-scale enzymatic synthesis of oligosaccharides.

The increasing recognition of the roles of carbohydrates in fundamental biological processes and their potential as new therapeutics has accentuated the requirement for access to large quantities of varying carbohydrate structures. During the past two years, tremendous advances have been made in the large-scale enzymatic synthesis of oligosaccharides using isolated enzymes or engineered whole cells. Glycosidase mutants, namely glycosynthases, have been constructed to increase both the yields and selectivity of the glycoside bond formation. The use of glycosyltransferases in oligosaccharide synthesis has been further improved by fusing a glycosyltransferase with a sugar nucleotide-synthesizing enzyme and by various routes of in situ sugar nucleotide regeneration. Moreover, several sugar nucleotides and oligosaccharides were produced economically by a combination of recombinant microorganisms harboring sugar nucleotide biosynthesis genes and a glycosyltransferase gene.