Biotransformation of enones with biocatalysts - two enone reductases from Astasia longa

The stereochemistry and mechanism in the reduction of the C-C double bond o f carvone by the cultured cells of Astasia longa, a nonchlorophyllous cell line classified in Euglenales, was studied. The reduction of the C-C double bond of carvone with the cultured cells involved the anti-addition of hydr ogen atom from the si face at the alpha-position and the re face at the bet a-position of carbonyl group. Two different enone reductases were isolated from the cultured cells of A. longa. Both reductases catalyzed stereospecif ically the anti-addition of hydrogen atoms from the si face at C-l and the re face at C-6. However, one of the reductases participated in a hydrogen t ransfer of the pro-4R hydrogen of NADH to C-6 position of carvone and the o ther used the pro-4S hydrogen of NADH. (C) 2000 Elsevier Science B.V. All r ights reserved.