Regulatory role of surfactants in the kinetics of glucose oxidase-catalyzed oxidation ofd-glucose by ferrocenium andn-butylferrocenium ions

Abstract

The effect of micelles of different surfactants (cationic, anionic, and neutral) on the kinetics of the glucose oxidase-catalyzed reduction of ferrocenium cations RFc+ (R=H, Bun) byd-glucose was studied by spectrophotometry. In micellar media of Triton X-100 and sodium dodecyl sulfate (SDS), the Michaelis dependence of the reaction rate on the HFc+ concentration is observed, while this dependence has an extreme character in cationic micelles of cetyltrimethylammonium bromide (CTAB). The nature and concentration of surfactants of all types have a slight effect on the rate of reduction of HFc+. The level of enzymatic activity is approximately equal in the case of Triton X-100 and CTAB and is considerably lower in the SDS micelles. On going from HFc+ to BunFc+, the reaction rate is maximum in the cationic CTAB micelles, the anionic SDS micelles exhibit almost no activity, and the activity has an intermediate value in neutral micelles of Triton X-100. The conditions are presented under which the micellar medium controls the catalytic activity of glucose oxidase with respect to ferrocenium cations.