Direct electrochemistry of Penicillium chrysogenum catalase adsorbed on spectroscopic graphite

The voltammetric studies of Penicillium chrysogenum catalase (PcCAT) adsorbed on spectroscopic graphite, showed direct electron transfer (DET) between its active site and the electrode surface. Analogous tests performed with the commercially available bovine catalase revealed that mammalian enzyme is much less efficient in the DET process. Both catalases were found capable to catalyse the electrooxidation of phenol, but differed in the specifics of catalytic action. At an applied potential of 0.45 V the non-linear regression showed the kinetics of the bioelectrochemical oxidation catalysed by the PcCAT obeyed the Hill equation with a binding constant K = 0.034 ± 0.002 M2 (Hill's coefficient n = 2.097 ± 0.083, R2 = 0.997), whilst the catalytic action of the bovine catalase was described by the Michaelis–Menten kinetic model with the following parameters: Vmax,app = 7.780 ± 0.509 μA, and KM,app = 0.068 ± 0.070 mol L− 1. The performance of the electrode reaction was affected by the electrode potential, the pH, and temperature. Based on the effect of pH and temperature on the electrode response in presence of phenol a tentative reaction pathway of its bioelectrocatalytic oxidation has been hypothesised. The possible application of these findings in biosensing phenol up to concentration 30 mM at pHs below 7 and in absence of oxidising agents (oxygen or H2O2) was considered.

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► Direct electrochemistry of fungal catalase adsorbed on graphite was examined.
► Bioelectrocatalytic oxidation of phenol on the enzyme electrodes was observed.
► PcCAT was proven more efficient in DET and bioelectrocatalysis than mammalian CAT.
► Effects of pH and temperature on the bioelectrocatalytic process were studied.
► Phenol biosensing was considered one of the possible applications of the study.