Novel reductase participation in the syn-addition of hydrogen to the CC bond of enones in the cultured cells of Nicotiana tabacum

A reductase isolated from cultured cells of Nicotiana tabacum has been characterized and used in the reduction of a CC bond adjacent to a carbonyl group. The stereochemistry of the latter reaction has been investigated by 2H NMR and mass spectroscopy. It was found that the reductase reduces stereospecifically the CC bond of verbenone and carvone by syn addition of hydrogen from the re face at the β-position and the re face at the α-position to the carbonyl group; the hydrogen atoms participating in the enzymatic reduction at the α- and β-positions originate from the medium (H2O) and the pro-4S hydrogen of NADPH, respectively.