Ferricenium salts instead of dioxygen in glucose oxidase catalysis. A direct interaction and analytical implications.

: The ferricenium salt FcH+BF4- behaves as a specific substrate of glucose oxidase acting instead of dioxygen with the effective parameters of the Michaelis-Menten equation kcat = 2.60 x 10(2) s-1 and KM = 2.7 x 10(-4) M at 25 degrees C, pH 6.8 and [D-glucose] = 0.001 M. The activity of glucose oxidase can easily be monitored by conventional UV-vis spectrophotometry at 617 nm following the bleaching of the ferricenium dye.