Protein engineering of bacterial K-amylases

K-Amylases constitute a very diverse family of glycosyl hydrolases that cleave K1C4 linkages in amylose and related polymers. Recent structural and mutagenic studies of archeael, mammalian and bacterial K-amylases 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 K-amylases have found widespread use in industrial processes, and much attention has been devoted to optimising these enzymes for the very harsh conditions encountered there. Stability has been a major area of focus in this respect, and several remarkably stable bacterial K-amylases have been produced by bioengineering techniques. Protein engineering studies of pH-activity profiles and of substrate specificities have also been initiated, although without much success. In the coming years it is likely, however, that the focus of K-amylase engineering will shift from engineering stability to these new areas. ß 2000 Elsevier Science B.V. All rights reserved.