Kinetic and amperometric study of the MtPerII peroxidase isolated from the ascomycete fungus Myceliophthora thermophila.

The enzyme MtPerII is a new peroxidase which has been isolated only recently from fungus Myceliophthora thermophila and has significant thermostability and stability at high HO concentrations. In the present work, an electrochemical kinetic study, based on cyclic voltammetry, is performed for the first time for the catalytic decomposition of HO by MtPerII, at 18°C. Leuco methylene blue (LMB) is used as a mediator and the catalytic and Michaelis constants are determined, assuming a Michaelis-Menten mechanism. Experimental evidence suggest the absence of inhibition by HO, for concentrations up to 16mM, and increasing catalytic activity for temperatures up to 50°C. Moreover, a modified electrode is constructed, by attempting the entrapment of MtPerII on a dodecanothiol self-assembled monolayer on gold. The modified electrode is studied chronoamperometrically in solutions containing methylene blue mediator and different concentrations of HO. It is shown that adsorbed MtPerII retains its activity and the modified electrode exhibits a considerably high linear region for the detection of HO. The experimental findings indicate that MtPerII is a new candidate for analytical and industrial applications.

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