Glucoseoxidase from Aspergillus niger in reverse micelles: pH and wo dependence

The well known enzymatic method for the determination of glucose in aqueous solution with the system glucose oxidase/peroxidase/o-dianisidine was modified in a way that enables the quantitative determination of glucose in various reverse micellar systems. For instance in the 0.1 M sodium-bis-(2-ethylhexyl)-sulfosuccinate/n-octane system the useable glucose measuring range is between 10 and 70 micrograms glucose per 3 ml micellar solution. Investigations concerning the influence of the pH-value and the wo-value on the enzyme activity of glucose oxidase in the system 0.1 M sodium-bis-(2-ethylhexyl) sulfosuccinate/n-octane led to a shift of the pH-optimum from pH 5.5-6.0 in aqueous solution, to pH 4.0, in reverse micellar solution. The bell-shaped wo-dependence of the enzyme activity, typical for many other enzymes, was not found for glucose oxidase at pH 4.0, and was less clearly visible at the other investigated pH-values with an optimum at wo = 5.6.