Effects of Exogenous Electron Donors on Epoxidation of Propylene Catalyzed by Methane Monooxygenase of Methylomonas sp. GYJ3
外源电子给体对甲烷单加氧酶催化丙烯环氧化反应活性的影响

Effect of exogenous electron donors on activity of MMO of Mehtylomonas sp. GYJ3 were studied. The results indicated that methane, methanol, formaldehyde and formate as electron donors were able to enhance the rates of propylene eposidation ct-alyzed by MMO. The initial concentration of these electron donors added to reaction system greatly influenced the raes of propylene epoxidation. At the optimum initial concentration of methane , methanol, formaldehyde and formate, the activities of MMO were stimulated to enhance 5. 3, 12. 7, 10 and 12. 4 fold of intrinsic activity, respectively. Methane and formaldehyde becomes toxic to MMO at high concentrations. Formate, an ideal electron donor, was shown to stimulate activity of MMO without apparent inhibition at relatively high concentrations up to 130um. The metabolism of methanol, the accumulation of propylene oxide and the activity of MMO in course of reaction time were studied with propylene epoxidation by restingcell of Mehtylmnonas sp. GYJ3 at initial concentration of 1. 5mmol/L methanol. The results revealed that the metabolic rate of methanol and regeneration rate of NADH were much higher that the rates of propylene epoxidation and almost unvaried with reaction time. However, the rates of propylene e-poxidation were lower with reaction time, suggesting that the propylene oxide was inhibitory to MMO at relatively high concentrations.