Study of catalase reversibility during multiple injections of H2O2 using online measurement by FFT continuous cyclic voltammetry

This work presents a new method for the determination of catalase activation reversibility upon injection of different concentrations of hydrogen peroxide (H2O2) based on fast Fourier transformation continuous cyclic voltammetry (FFTCCV). The spectroscopic and cyclic voltammetric data demonstrated that catalase could rapidly decompose H2O2 at concentrations below 40 mM. Also, the catalase activity gradually decreased at higher concentrations of H2O2. In addition, the calculated kinetics model of suicide inhibition demonstrated that the catalase irreversibility was triggered at the concentration of 80 mM. FFTCCV data by multiple injections of H2O2 revealed that the catalase activity could be recovered at 10, 20, 40, and 60 mM after 6, 4, 3, and 2 injections of H2O2, respectively. H2O2 at concentrations above 40 mM was not fully decomposed and remained in the solution after the catalase reaction. The maximum reversibility of the catalase activity was observed for the concentration of 10 mM, when H2O2 concentration drastically decreased within a few seconds of the reaction. Our data shows that the FFTCCV method can be recruited to monitor and evaluate enzymatic reactions.