Selectivity of Enzymes
One of the important properties of enzymes is to select from a mixture (racemic pairs, prochiral or meso-compounds or diastereometric mixtures), a compound, which is enantiomerically pure (enantiomers are a class of isomers that are mirror images of each other and occur in mixtures). This is described as enzymatic resolution of substrates and can be achieved by anyone of the following three methods. (i) The enzyme esterifies only a single enantiomer of a racemic substrate and thus allows its separation. Enol esters can be used as transesterification reagents to force the enzymatic process to proceed irreversibly in the desired forward direction. (ii) Enzymatic resolution has also been realized by certain hydrolytic enzymes through the use of additional racemization catalysts, which keep on converting the enantiomer that is not a substrate for the enzyme into the enantiomer, which is the substrate.