Efficient Artificial Electron Acceptors for Monoamino Oxidase in Bioelectrooxidation of Monoamines: Phenothiazine Dyes

Catalytic properties of monoamino oxidase (MAO) in a homogeneous reaction of oxidation and a heterogeneous reaction of bioelectrocatalytic oxidation of benzylamine by derivatives of phenothiazine and phenoxazine (artificial electron acceptors) is studied. The efficiency of electroenzymic catalysis involving Methylene Blue and MAO immobilized on the electrode is comparable to that of homogeneous enzymic catalysis. When immobilized in a film of polymer electrolyte Eastman AQ-29, Methylene Blue and Toluidine Blue efficiently carry electrons from the reduced redox center of immobilized MAO onto a glassy-carbon electrode. Dependence of the oxidation current of these compounds on the concentration of the benzylamine substrate is studied and it is shown that the enzymic reaction is the limiting stage in a bioelectrocatalytic process. This conclusion gives grounds for using the dependence of the anodic current on the monoamine concentration as a calibration plot when assaying biogenic amines.