The concept of the α-amylase family: A rational tool for protein engineering of glycoenzymes

Abstract

A multi-specific enzyme, neopullulanase (EC 3.2.1.135) catalyzes the hydrolysis of α-1,4- and α-1,6-glucosidic linkages, as well as transglycosylation to form α-1,4- and α-1,6-glucosidic linkages. Based on the series of experimental results using neopullulanase, we pointed out the structural similarity and the common catalytic mechanism of the enzymes that catalyze these four reactions, and thus, proposed and defined the concept of α-amylase family. Mutational analyses provided the evidence that the only one active center of neopullulanase participate in all four reactions; the hydrolysis of α-1,4- and α-1,6-glucosidic linkages and transglycosylation to form α-1,4- and α-1,6-glucosidic linkages. Structural analyses provided the conclusive proof that only the one active center of neopullulanase participates in all four reactions. We have been trying to interconvert glucanohydrolases/glucanotransferases, and change their specificity and create tailor-made industrially useful enzymes based on the concept of the α-amylase family. The concept of the α-amylase family is demonstrated here again as a rational tool for protein engineering of glycoenzymes. ©2006 FCCA (Forum: Carbohydrates Coming of Age).