OXIDATIVE BIOTRANSFORMATIONS BY MICROORGANISMS - PRODUCTION OF CHIRALSYNTHONS BY CYCLOPENTANONE MONOOXYGENASE FROM PSEUDOMONAS SP NCIMB-9872

Cyclopentanone monooxygenase, an NADPH- plus FAD-dependent enzyme indu ced by the growth of Pseudomonas sp. NCIMB 9872 on cyclopentanol, has been utilised as a biocatalyst in Baeyer-Villiger oxidations. Washed w hole-cell preparations of the microorganism oxidised 3-hexylcyclopenta none in a regio- but not enantioselective manner to give predominantly the racemic gamma-hexyl valerolactone. Similar preparations biotransf ormed 5-hexylcyclopent-2-enone exclusively by regio- plus enantioselec tive oxidation to the equivalent alpha,beta-unsaturated (S)-(+)-delta- hexyl valerolactone (ee = 78%), with no reductive biotransformations c atalysed by either EC 1.1. x. x- or EC 1.3.x.x-type dehydrogenases. An equivalent biotransformation of 5-hexylcyclopent-2-enone was catalyse d by highly-purified NADPH- plus FAD-dependent cyclopentanone monooxyg enase from the bacterium. The regio- plus enantioselective biotransfor mation by the pure enzyme of 2-(2'-acetoxyethyl)cyclohexanone yielded optically-enriched (S)-(+)-7-(2'-acetoxyethyl)-2-oxepanone (ee = 72%). The same biotransformation when scaled up again provided optically-en riched (S)-(+)-epsilon-caprolactone which was converted, using methoxi de, to (S)-(-)-methyl 6,8-dihydroxyoctanoate (ee = 42%), thereby provi ding a two-step access from the substituted cyclohexanone to this impo rtant chiron for the subsequent synthesis of (R-(+)-lipoic acid. Some characteristics of pure NADPH- plus FAD-dependent cyclopentanone monoo xygenase were determined including the molecular weight of the monomer ic subunit (50000) of this homotetrameric enzyme, and the N-terminal a mino acid sequence up to residue 29, which includes a putative flavin nucleotide-binding site.