Quantitative assessment of oxidoreductase and catalase enzymatic activity in model systems for catalyzed degradation of glucose and hydrogen peroxide

Abstract

The study quantitatively characterizes the process parameters that enable glucose removal via the glucose oxidase/catalase (GO/CAT) enzymatic system in acidic model solutions. Screening across a pH range of 4.0–5.5 and temperatures from 25 to 50 °C identified pH 5.5 and 40 °C as optimal for GO, with activity at pH 5.0 reduced by only 2.5 %. Under these conditions, catalase retained 86.5 % of its maximal activity. Dissolved oxygen concentration was found to be a key factor that impacts glucose conversion. Without oxygenation (initial dissolved oxygen concentration of 7.5–8.0 mg/L), 6-h reactions achieved 29.0 % glucose removal. Additional oxygenation (9.5–11.0 mg/L), using 1000 U GO with varying CAT activities (0, 1000, 3000, 4500 U), yielded glucose reductions of 2.9 %, 57.0 %, 75.9 %, and 93.4 %, respectively, from an initial glucose concentration of 27 g/L. At an oxygen concentration of 12.5–14.0 mg/L with 1000 U GO and 3000 U CAT, complete glucose oxidation was achieved within 4 h. Hydrogen peroxide exhibited concentration-dependent inhibition of GO at pH 5.5/40 °C, with relative activities of 82.6 %, 80 %, and 70.4 % at 45, 60, and 75 mmol/L H₂O₂, respectively. Thermal stability assessment revealed that GO retained 90.4 % of its activity after 6 h, whereas CAT retained 96.9 %. Pasteurization (90 °C, 10 min) fully inactivated GO and caused 84.9 % loss of CAT activity. These findings establish practical operational guidelines — GO:CAT ≥1:3 and oxygen concentration >9.5 mg/L for efficient glucose depletion under slightly acidic pH conditions and elevated temperature conditions.