Enzymatic activity of L-amino acid oxidase from snake venom Crotalus adamanteus in supercritical CO2

L-amino acid oxidase (L-AAO) from snake venom Crotalus adamanteus was successfully tested as a catalyst in supercritical CO₂ (SC-CO₂). The enzyme activity was measured before and after exposure to supercritical conditions (40°C, 110 bar). It was found that L-AAO activity slightly increased after SC-CO₂ exposure by up to 15%. L-AAO was more stable in supercritical CO₂ than in phosphate buffer under atmospheric pressure, as well as in the enzyme membrane reactor (EMR) experiment. 3,4-Dihydroxyphenyl-L-alanine (L-DOPA) oxidation was performed in a batch reactor made of stainless steel that could withstand the pressures of SC-CO₂, in which L-amino acid oxidase from C. adamanteus was able to catalyze the reaction of oxidative deamination of L-DOPA in SC-CO₂. For the comparison L-DOPA oxidation was performed in the EMR at 40°C and pressure of 2.5 bar. Productivity expressed as mmol-s of converted L-DOPA after 3?h per change of enzyme activity after 3?h was the highest in SC-CO₂ (1.474?mmol?U^?1), where catalase was present, and the lowest in the EMR (0.457?mmol?U^?1).