CARBONYL REDUCTASES - THEIR FUNCTIONS AND APPLICATION TO THE PRODUCTION OF OPTICALLY-ACTIVE COMPOUNDS

Novel NADPH-dependent carbonyl reductases which catalyze the stereospecific reductions of carbonyl compounds have been purified from various microorganisms and characterized. The enzymes "polyketone reductase" purified from Candida parapsilosis and Mucor ambiguus specifically catalyze the reduction of various prochiral cyclic diketones, yielding the cor-responding (R)- and (S)-alcohols, respectively. Aldehyde reductase from Sporobolomyces salmonicolor and carbonyl reductase from C. macedoniensis catalyze the stereospecific reduction of various aliphatic and aromatic ketones and aldehydes. Ketopantoic acid reductase from Pseudomonas maltophilia and an FMN-dependent alcohol dehydrogenase from Nocardia asteroides, catalyze the reduction of ketopantoic acid to D-pantoic acid and the oxidation Of L-pantoyl lactone to ketopantoyl lactone, respectively. These enzymes were successfully applied to the synthesis of chiral intermediates for the synthesis of D-pantothenic acid and L-carnitine. In all cases, the troublesome optical resolution of racemic mixtures, which is unavoidable in coneventional organic synthetic process for such optically active substances, is omitted.