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Kinetic study of hydrogen peroxide decomposition by catalase in a flow-mix microcalorimetric system

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Abstract

The kinetics of hydrogen peroxide decomposition by the enzyme catalase was studied at pH 7.4 in the temperature range 10–30 °C. Experiments were performed by the LKB-2277 Thermal Activity Monitor equipped with a flow-mix cylinder. The calorimetric reaction unit was schematised as a tubular reactor operating under plug-flow conditions. A first-order kinetic expression, with respect to both the substrate and the enzyme, was used to describe the rate of hydrogen peroxide decomposition. Regression analysis of calorimetric data provided a molar reaction enthalpy of −87.55 kJ mol−1 and an activation energy of 11 kJ mol−1. Analysis of model residuals and the normal probability plot indicated that the results obtained were statistically significant.

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... Catalase is an enzyme that is found in almost every living organism exposed to oxygen and is known to break down hydrogen peroxide (H 2 O 2 ) into oxygen and water so as to protect cells from oxidative stress. 27 The reaction is appreciably exothermic and can be used to test the performance of the pyrometer. Note that since oxygen bubbles are generated during this reaction, an open-ended cell is used to avoid the thermal isolation induced by the bubble. ...
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... It is known that the H 2 O 2 decomposition activation energy varies from 30 to 80 kJ/mol [21,22] in the presence of transition metal ions when a free-radical H 2 O 2 decomposition takes place. However, the activation energy is much lower for the H 2 O 2 decomposition reaction in the presence of catalase [23] or colloidal iron oxohydroxides [24] and ranges from 7 to 11 kJ/mol, when H 2 O 2 decomposes by ion-molecular way. Different forms of kinetics curves were another pointer on the H 2 O 2 decomposition mechanism change at different pH 0 (Fig. 8). ...
... Once S OE is reached, a pulse of H 2 O 2 is added and the oxygen level increases ( Fig. 1 period a) because hydrogen peroxide is broken down by the enzyme catalase producing oxygen (Equation (3)). 12 This process has been widely studied in the literature: 10,13,14 ...
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... It is known that the H 2 O 2 decomposition activation energy varies from 30 to 80 kJ/mol [21,22] in the presence of transition metal ions when a free-radical H 2 O 2 decomposition takes place. However, the activation energy is much lower for the H 2 O 2 decomposition reaction in the presence of catalase [23] or colloidal iron oxohydroxides [24] and ranges from 7 to 11 kJ/mol, when H 2 O 2 decomposes by ion-molecular way. Different forms of kinetics curves were another pointer on the H 2 O 2 decomposition mechanism change at different pH 0 (Fig. 8). ...
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