Electrochemical approach for monitoring the catalytic action of immobilized catalase

Abstract Heterogeneous enzymatic activity of fungal catalase from Penicillium chrysogenum in the hydrogen peroxide (H 2 O 2 ) disproportionation reaction in a neutral aqueous buffer solution has been examined by means of constant-potential chronoamperometry. A recently developed catalytic peroxide electrode has been used as both an electrochemical detector and a high-speed low-noise stirrer. The determination of immobilized enzyme activity has been performed in an electrochemical system containing a sample of immobilized fungal catalase (from P. chrysogenum ) and a rotating catalytic electrode sensitive to H 2 O 2 concentration placed at a close distance to the sample. Heterogeneous catalytic activities of fungal catalase for H 2 O 2 decomposition have also been assayed in the presence of 0.5 and 1.0% ethanol and methanol. Alterations of catalase catalytic action have been found in the presence of alcohols: while in the absence of alcohols its kinetics obeys the Michaelis–Menten mechanism, in the presence of alcohols it is described by Hill’s model. The apparent kinetic constants of the enzyme-catalyzed process have been proven to differ depending on the type of alcohol and its amount in the medium. The obtained results imply that the use of the electrocatalytic approach can be considered a promising alternative for kinetic characterization of immobilized enzymes, provided that the enzyme substrate is electrochemically active.