Mechanism for High Stability of Liposomal Glucose Oxidase to Inhibitor Hydrogen Peroxide Produced in Prolonged Glucose Oxidation

Abstract

Glucose oxidase (GO) was encapsulated in the liposomes composed of POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) to increase the enzyme stability through its decreased inhibition because of hydrogen peroxide (H(2)O(2)) produced in the glucose oxidation. The GO-containing liposomes (GOLs) were completely free of the inhibition even in the complete conversion of 10 mM glucose at 25 degrees C because the H(2)O(2) concentration was kept negligibly low both outside and inside liposomes throughout the reaction. It was interestingly revealed that the H(2)O(2) produced was decomposed not only by a slight amount of catalase originally contained in the commercially available GO but also by the lipid membranes of GOL. As compared to the GOL-catalyzed reaction, the free GO-catalyzed reaction more highly accumulated H(2)O(2) because of the more rapid glucose conversion despite containing free catalase, leading to the completely inhibited GO before reaching a sufficient glucose conversion. This suggested that only the liposomal catalase could continue to catalyze the H(2)O(2) decomposition. The effect of the glucose oxidation rate, i.e., the H(2)O(2) production rate on the liposomal GO inhibition, was also examined employing the various GOLs with different permeabilities to glucose present in their external phase. It was concluded that the liposomal GO free of the inhibition could be obtained when the GOL-catalyzed H(2)O(2) formation rate was limited by such a suitable lipid bilayer as POPC membrane so that the rate was well-balanced with the sum of the above two H(2)O(2) decomposition rates. The highly stable GOL obtained in the present paper was shown to be a useful biocatalyst for the prolonged glucose oxidation.

Spatial Distance Effect of Bienzymes on the Efficiency of Sequential Reactions in a Microfluidic Reactor Packed with Enzyme-immobilized Microbeads

“…31 It was reported that the stability of the GOx enzyme could be greatly improved by adding catalase enzymes to remove H2O2 quickly. 32 Thus, there is less chance of inhibiting GOx enzymes by the intermediate product in reactor I than in the other two types of reactors, because the intermediate product can be quickly converted to the final product by having HRP enzymes nearby GOx in reactor I. After rinsing the three microreactors with a buffer solution extensively, we examined whether they can be reused.…”

Covalent conjugation of tetrameric bovine liver catalase to liposome membranes for stabilization of the enzyme tertiary and quaternary structures

“…BLC is potentially useful for eliminating H 2 O 2 produced in various enzymatic oxidation reactions such as the air oxidation of glucose catalyzed by glucose oxidase [12,13]. The BLC activity is, however, difficult to be maintained in practical reaction conditions.…”

Immobilized glucose oxidase on different supports for biotransformation removal of glucose from oligosaccharide mixtures

“…This enzyme is of considerable commercial importance. GOD is widely used in clinical and chemical analyses as well as in food industry [2][3][4][5] for the removal of glucose [6] or oxygen from food products and for production of gluconic acid [7,8].…”