MICROBIAL CARBONYL REDUCTASES - THEIR DIVERSITY AND APPLICATION TO THE SYNTHESIS OF OPTICALLY-ACTIVE ALCOHOLS

New NADPH-dependent carbonyl reductases which catalyze stereospecific reductions of carbonyl compounds have been purified from various microorgansms and characterized. The enzymes "polyketone reductase" from Candida parapsilosis and Mucor ambiguus specifically catalyze reduction of various prochiral cyclic diketones, yielding the corresponding (R) - and (S) - hydroxyketones, respectively. Aldehyde reductase from Sporobolomyces salmonicolor and carbonyl reductase from C. macedoniensis catalyze stereospecific reduction of various aliphatic and aromatic ketones and aldehyds. Ketopantoic acid reductase from Pseudomonas maltophilia and an FMN-dependent alcohol dehydrogenase from Nocardia asteroides, catalyze reduction of ketopantoic acid to D-pantoic acid and oxidation of L-pantoyl lactone to ketopantoyl lactone. These enzymes were successfully applied to the synthesis of chiral intermediates for the synthesis of D-pantothenic acid and L-carnitine.