Biocatalytic methods of olefin oxidation provide a better chemo-, regio- and stereo-selectivity and operate under very mild conditions. Chiral epoxides and 1,2-diols are important building blocks for the synthesis of biologically active compounds. They can be obtained from the enzymatic kinetic resolution of the readily available racemic epoxides using epoxide hydrolases.

Epoxide hydrolases are cofactor-independent enzymes that can be used with ease outside the cell environment. They are found in mammalian, bacterial, fungal, plant and insect cells. The enzymatic enantioselective hydrolysis of epoxides is usually carried out in aqueous reaction media with whole microbial cells. The drawbacks of this method include the low solubility of these epoxides in the aqueous buffer systems and the spontaneous hydrolysis of the epoxide leading to the undesired racemic epoxides and diols. These problems can be overcome by using organic solvents as the reaction medium. However, many common organic solvents are toxic to the free enzyme and the enzyme activity is drastically reduced.

In this study, a crude enzyme preparation from B. bassiana was immobilized by entrapment in alginate beads for the resolution of styrene oxide and indene oxide in the presence of organic solvents. The immobilized enzyme could be successfully employed in the resolution of styrene oxide at more than 20g/l with enantio-selectivities of more than 90%. On recycling, the stabilized immobilized enzyme maintained its activity after five cycles of batch hydrolyses. Several organic solvents are being examined at different conditions for optimal yield and selectivity.

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