Purification and characterization of a novel carbonyl reductase involved in oxidoreduction of aromatic β-amino ketones/alcohols

Aromatic beta-amino ketones/alcohols such as adrenalone play an important role in some stereoselective synthesis of pharmaceuticals. Unfortunately, the transformation of aromatic beta-amino ketones to their chiral alcohols has been carried out chemically as no corresponding biocatalyst has been available. Here, a novel carbonyl reductase responsible for the reduction of adrenalone to (R)-(-)-epinephrine was identified and characterized from Kocuria rhizophila. This enzyme was purified to homogeneity by ammonium sulfate precipitation followed by ion-exchange column chromatography, hydrophobic chromatography and gel chromatography. The purified enzyme yielded pure (R)-enantiomer product with high activity and utilized NADH as the cofactor. The enzyme had special significance by showing selectivity for many aromatic beta-amino ketones/alcohols such as 2-amino-acetophenone, 2-amino-4'-hydroxyacetophenone, isoproterenol and ephedrine. The maximum reaction rate (V-max) and apparent Michaelis-Menten constant (K-m) for adrenalone and NADH were 14.62 mu mol/(min mg) protein and 0.189 mM, 11.66 mu mol/(min mg) protein and 0.204 mM respectively. These properties ensure the enzyme a promising future for industrial application as a replacement of chemical synthesis of aromatic beta-amino chiral alcohols. (C) 2014 Elsevier Ltd. All rights reserved.