Protein engineering of bacterial alpha-amylases

alpha -Amylases constitute a very diverse family of glycosyl hydrolases tha t cleave alpha1 --> 4 linkages in amylose and related polymers. Recent stru ctural and mutagenic studies of archeael, mammalian and bacterial alpha -am ylases have resulted in a wealth of information on the catalytic mechanism and on the structural features of this enzyme class. Because of their high thermo-stability, the Bacillus alpha -amylases have found widespread use in industrial processes, and much attention has been devoted to optimising th ese enzymes for the very harsh conditions encountered there. Stability has been a major area of focus in this respect, and several remarkably stable b acterial alpha -amylases have been produced by bioengineering techniques. P rotein engineering studies of pH-activity profiles and of substrate specifi cities have also been initiated, although without much success. In the comi ng years it is likely, however, that the focus of alpha -amylase engineerin g will shift from engineering stability to these new areas. (C) 2000 Elsevi er Science B.V. All rights reserved.