Abstract
Glycosynthases are mutant glycosidases, genetically engineered to catalyse the synthesis of oligosaccharides. A study by Faijes et al. in this issue of the Biochemical Journal has expanded the ability of glycosynthases to catalyse the polymerization of carbohydrates to form unnatural oligosaccharide products that can attain unique crystalline forms. These findings reinforce the potential of glycosynthases as interesting and important tools for the enzymic synthesis of novel carbohydrates with specific and controlled structures.