Electrooxidation mechanism of biogenic amines at amine oxidase modified graphite electrode

Amine oxidase (AO, EC. 1.4.3.6) was previously shown to be a very efficient biological recognition element of amperometric biosensors for monitoring b iogenic amines. The enzyme was effectively working in both mono- and bienzy me electrode designs, based on either a direct or a mediated electron-trans fer pathway. This work focuses on the elucidation of the electron-transfer mechanism of the monoenzymatic unmediated AO-modified biosensor. The observ ed unmediated catalytic currents were assumed to be caused by (i) a direct electron-transfer process, (ii) the electrooxidation of the formed product, or (iii) their combination. Experiments supporting these assumptions are d iscussed in detail.