COMPARISON OF REACTIVITY OF ALKENE EPOXIDATION WITH INTACT-CELLS AND CELL-FREE-EXTRACTS OF METHYLOSINUS-TRICHOSPORIUM OB3B

Kinetic studies of a series of alkene epoxidations (ethylene, propylen e and 1-butene) with intact cells and cell-free extracts of Methylosin us trichosporium OB3b were carried out. For the epoxidation with intac t cells, V-max values were independent of the type of alkenes. K-m val ues, however, were remarkably different, and the order was ethylene < propylene < 1-butene. The results suggest that the reactivity of alken e epoxidation with intact cells of M. trichosporium OB3b strongly depe nds on the affinity of alkene and methane monooxygenase. For cell-free extracts, V-max values for ethylene and propylene were almost the sam e. V-max value for 1-butene was extremely small. K-m values were remar kably different, and the order was ethylene < propylene < 1-butene. On the comparison of intact cells and cell-free extracts of M. trichospo rium OB3b, the K-m value of ethylene with intact cells was much smalle r than that with cell-free extracts, indicating that ethylene is more easily incorporated into the cells. On the other hand, propylene and 1 -butene are not easily incorporated on comparison of the K-m values of intact cells with those of the cell-free extracts. These results indi cate that the cell membrane may act to avoid higher alkenes.