Fluorimetric–enzymatic determination of glucose based on labelled glucose oxidase Original Research Article

The main problem of enzymatic determinations based on the intrinsic fluorescence of enzymes is the wavelength range at which these compounds are excited (usually in the UV region). This study presents a new alternative which partially avoids this problem. It is based on a prior coupling reaction of the enzyme to a fluorescent reagent which has optical properties in the visible region. The method is applied to the enzymatic determination of glucose, with glucose oxidase (GOx) coupled to 7-hydroxycoumarin-4-acetic acid as the fluorescent reagent. The labelling procedure as well as the reaction conditions are studied and the origin of the analytical signal is discussed. The method gives a linear response to glucose concentration from 5.0×10−4 to 6.0×10−3 M and is applied to glucose determination in fruit juices with good results.