Enantioselective biotransformations using rhodococci

The use of enzymes and whole cells in enantioselective biotransformation reactions is briefly reviewed. A Rhodococcus strain is shown to possess nitrile hydratase and amidase activity. The organism can be used for the enantioselective biotransformation of racemic α-amino amides to (S) α-amino acids with an enantiomeric excess (ee) of > 98%. Enantioselectivity is effectively time independent allowing easy quantitative conversion of racemic mixtures into enantiomerically pure α-amino amides and α-amino acids. The reaction is effective for a wide range of α-substituents. The pH-dependence of the reaction indicates that the α-amino amide is bound to the amidase enzyme in its neutral unprotonated form.