主催: The Society of Chemical Engineers, Japan
The reactivity of the immobilized glucose oxidase-containing liposome (IGOL) prepared in our previous work is improved by incorporating the channel protein OmpF into the membrane as well as by entrapping catalase (CA) together with glucose oxidase (GO) inside the liposome. CA is for decomposing hydrogen peroxide since it is more rapidly produced in the presence of OmpF enhancing the glucose permeation. Firstly, the GO plus CA-containing liposome (GOCAL) is prepared and characterized. The remarkable protection effect of the membrane on CA inside liposome at 40°C is verified from the fact that the CA activity efficiency, defined as the observed CA activity relative to the intrinsic activity of the GOCAL, is much more stable compared to the activity of free CA. Secondly, the OmpF is incorporated into the GOCAL membranes. The highest value of the GO activity efficiency, defined in the same way as above, of the system (GOCAL-OmpF) is obtained when 5 OmpF molecules are charged in one liposome, giving the 17 times greater GO activity efficiency than that for the GOCAL and leaking neither GO nor CA at 40°C. Finally, the GOCAL-OmpF is covalently immobilized to the chitosan gel beads. The performances of this novel biocatalyst (IGOCAL-OmpF) are examined by following the change in the glucose conversion as well as the remaining GO activity with the successive 15 h-air oxidations for the repeated use at 40°C in an airlift bioreactor. The IGOCAL-OmpF shows higher reactivity and reusability than the IGOL as well as the OmpF-incorporating IGOL (IGOL-OmpF). Due to the absence of CA, the IGOL-OmpF is least stable and results in drastically inhibited GO.
