FLUOROMETRIC-ENZYMATIC DETERMINATION OF GLUCOSE BASED ON LABELED GLUCOSE-OXIDASE

The main problem of enzymatic determinations based on the intrinsic fl uorescence of enzymes is the wavelength range at which these compounds are excited (usually in the UV region). This study presents a new alt ernative which partially avoids this problem. It is based on a prior c oupling reaction of the enzyme to a fluorescent reagent which has opti cal properties in the visible region. The method is applied to the enz ymatic determination of glucose, with glucose oxidase (GOx) coupled to 7-hydroxycoumarin-4-acetic acid as the fluorescent reagent. The label ling procedure as well as the reaction conditions are studied and the origin of the analytical signal is discussed. The method gives a linea r response to glucose concentration from 5.0 x 10(-4) to 6.0 x 10(-3) M and is applied to glucose determination in fruit juices with good re sults. (C) 1998 Elsevier Science B.V.