NOVEL REDUCTASE PARTICIPATION IN THE SYN-ADDITION OF HYDROGEN TO THE C=C 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 C=C bond adjacent to a c arbonyl group, The stereochemistry of the latter reaction has been inv estigated by H-2 NMR and mass spectroscopy. It was found that the redu ctase reduces stereospecifically the C=C bond of verbenone and carvone by syn addition of hydrogen from the re face at the beta-position and the re face at the alpha-position to the carbonyl group; the hydrogen atoms participating in the enzymatic reduction at the alpha- and beta -positions originate from the medium (H2O) and the pro-4S hydrogen of NADPH, respectively.