Hydrolysis and Transglycosylation Reaction Specificity of Cyclodextrin Glycosyltransferases

The α-amylase family is a large group of enzymes that act on α-glycosidic bonds. Within this family, about twenty different reaction and product specificities can be found, including exo/endo-specificity, preferencefor α-(1, 4)- or α-(1, 6)-glycosidic bonds, and hydrolysis/transglycosylation reaction specificity. The combinationof three-dimensional structure elucidation and the biochemical characterization of dozens of site directed mutants has yielded a detailed insight into the catalytic mechanism employed by α-amylase family enzymes. Nevertheless, the variation in reaction and product specificity is far from understood. The purpose of this review is to give an overview of recent developments in the understanding of the hydrolysis and transglycosylation reaction specificity within cyclodextrin glycosyltransferase (CGTase), which is one of the best studied α-amylase family enzymes.