Probing enzyme specificity

Despite the widespread exploitation of enzymes for synthetic purposes in both academic and industrial applications, little is known about the factors that determine enzyme specificity. In view of the increasingly broad spectrum of unnatural substrate structures that synthetically useful enzymes are required to handle, it is becoming essential to delineate the enzyme-substrate interactions that regulate structural specificity and stereospecificity. This will then permit the identification of the enzymes best suited to transforming new substrate structures into the desired chiral synthons. Such knowledge of the factors controlling and determining optimum active site binding and orientation of any potential substrate structure will also facilitate the tailoring of enzyme specificity by protein engineering. Some results of initial studies probing the specificities of esterases and oxidoreductases of synthetic value, and of modifying their properties by site-directed mutagenesis, are described.