Protein engineering of glucoamylase to improve industrial performance - A review

Glucoamylase is produced in higher tonnage than almost any other industrial enzyme. However, glucoamylase would be even more useful if it were more th ermostable and selective in producing glucose. Extensive wort; to improve t hese properties has been conducted by site-directed mutagenesis of selected amino acid residues. Combining favorable mutations has decreased the abili ty of the enzyme to produce isomaltose, the main byproduct, in the glucoamy lase-catalyzed production of glucose by almost half, has increased enzyme t hermostability fourfold, and has increased enzyme activity by 15%. In addit ion, others have successfully improved catalytic efficiencies for maltose h ydrolysis over isomaltose hydrolysis by mutations of glucoamylase. This art icle will review the improvements that have been made in glucoamylase indus trial properties by protein engineering.