The chemical modification of enzymatic specificity

The chemical modification of enzymes has played and will continue to play an important role in probing the mechanism of enzyme activity. This technique can be utilized for identification of those individual amino acid residues responsible for the catalytic properties of the entire protein. In chemical modification experiments, changes in enzymatic specificity have been noted, but often not predicted. However, in recent years, rational approaches for the alteration of enzymatic properties have become feasible by means of site-specific mutagenesis and chemical methodology. In the first method, one amino acid can be replaced by a new one; in the second method, not only can new amino acid residues be introduced but also new catalytic entities (such as flavins) can be affixed to the protein molecule. Both methodologies are in their infancy, yet they represent a potentially powerful approach toward the design and synthesis of enzymes possessing new specificities.