Effects of Calcium and Vanadium Ions on the Epoxidation of Cyclohexene with H2O2 Catalyzed by Vanadium Bromoperoxidase

Vanadium bromoperoxidase (V-BPO) from a marine macro-alga Corallina officinalis can catalyze the epoxidation of cyclohexene in the presence of KBr to form epoxycyclohexane using H ₂ O ₂ as the oxidant. A process intensification strategy has been developed by the integration of V-BPO pretreatment, continuous feeding of H ₂ O ₂ , and optimizing reaction conditions in order to improve the epoxidation productivity. The BPO activity and thermostability increased significantly when the V-BPO solution was dialyzed with a buffer containing 1.0 mmol/L vanadium ion and 1.0 mmol/L calcium ion. The apparent enzyme activity was improved when the H ₂ O ₂ was fed continuously using a constant flow pump. When combined with the optimal reaction conditions (including buffer, pH, temperature, enzyme concentration, and KBr and H ₂ O ₂ concentrations), the space-time yield of epoxycyclohexane and its yield to hydrogen peroxide reached 4.79 g/(L · h) and 74%, respectively. These values are 78% increasing than the highest values reported previously.