The fluorescence emission of the apo-glucose oxidase from Aspergillus niger as probe to estimate glucose concentrations.
We developed a new method of glucose sensing using an inactive form of glucose oxidase from Aspergillus niger. Glucose oxidase was rendered inactive by removal of the FAD cofactor. The resulting apo-glucose oxidase still binds glucose as observed from a decrease in its intrinsic tryptophan fluorescence. 8-Anilino-1-naphthalenesulfonic acid (ANS) was found to bind spontaneously to apo-glucose oxidase as seen from an enhancement of the ANS fluorescence. The steady state intensity of the bound ANS decreased 25% upon binding of glucose, and the mean lifetime of the bound ANS decreased about 40%. These spectral changes occurred with a midpoint from 10 to 20 mM glucose, which is comparable to the K(D) of holo-glucose oxidase. These results suggest that apo-glucose oxidase can be used as a reversible nonconsuming sensor for glucose.
D'Auria
S
S
Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, Maryland, 21201, USA.
Herman
P
P
Rossi
M
M
Lakowicz
J R
JR
D000817:Anilino Naphthalenesulfonates; D001051:Apoenzymes / Q000378:metabolism*; D001234:Aspergillus niger / Q000201:enzymology; D015374:Biosensing Techniques / Q000379:methods*; D001786:Blood Glucose / Q000032:analysis; D005456:Fluorescent Dyes / Q000378:metabolism*; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000378:metabolism*
D000817:Anilino Naphthalenesulfonates; D001051:Apoenzymes; D001786:Blood Glucose; D005456:Fluorescent Dyes; C027132:1-anilino-8-naphthalenesulfonate; D005949:Glucose Oxidase; D005947:Glucose