Recent Advances in Enzyme Engineering through Incorporation of Unnatural Amino Acids

The development of new enzyme engineering technologies has been actively pursued as the industrial use of biocatalysts is rapidly increasing. Traditional enzyme engineering has been limited to changing the functional properties of enzymes by replacing one amino acid with the other 19 natural amino acids. However, the incorporation of unnatural amino acids (UAAs) has been exploited to manipulate efficient enzymes for biocatalysis. This has been an effective enzyme engineering technique by complementing and extending the limits of traditional enzymatic functional changes. This review paper describes the basic functions of the new functional groups of UAAs used in enzyme engineering and the utilization of UAAs in the formation of chemical bonds in the proteins. The recent developments of UAA-mediated enzymology and its applicability in industry, pharmaceutical and other research areas to overcome the limitations of existing enzymes is also emphasized.