ALKENE MONOOXYGENASE-CATALYZED WHOLE-CELL EPOXIDATION IN A 2-LIQUID PHASE SYSTEM

Whole cell biocatalysts are being examined closely by industry for asy mmetric synthesis because of their inherent enantioselectivity. In thi s study, Mycobacterium M156 was used to convert allyl phenyl ether (AP E) to the chiral intermediate phenyl glycidyl ether (PGE). Unfortunate ly, the large-scale production of PGE is difficult due to its hydropho bic nature and the product inhibition of the monoxygenase enzyme carry ing out the reaction; hence, in order to address these problems, this work explored the possibility of producing PGE in an aqueous-organic t wo-phase system and examined the influence of system parameters on the rate and duration of epoxidation. Hexadecane was chosen as the most s uitable solvent since it did not result in molecular toxicity and prov ided a good reservoir for both the PGE and APE. Increased mixing enhan ced the rate of epoxidation, presumably by increasing the interfacial area for mass transfer and enhancing mixing in the bulk phases. Increa sed substrate concentration in the organic phase resulted in ''pseudo' ' Michealis-Menten type behavior with the maximum extrinsic rate measu red at 6.7 nmol mg(-1) dwt min(-1), with a half-rate constant (K-m) of 0.144 mM. PGE production ceased after around 2 h; reasons such as pha se toxicity, lack of inactivated over time by intracellular PGE, altho ugh APE and hexadecane may have played a small role. (C) 1998 Elsevier Science Inc.