INFLUENCE OF PH, BENZOIC-ACID, EDTA, AND GLUTATHIONE ON THE PRESSURE AND OR TEMPERATURE INACTIVATION KINETICS OF MUSHROOM POLYPHENOLOXIDASE/

The pressure and/or temperature inactivation of mushroom polyphenoloxi dase (PPO) in the absence and presence of EDTA, benzoic acid, and glut athione was studied on a kinetic basis. In addition, the effect of pH was evaluated. The temperature stability of PPO at atmospheric pressur e increased with increasing pH up to pH 6.5. The pressure stability of PPO at room temperature (25 degrees C) also increased with increasing pH. EDTA slightly increased the thermal stability of the enzyme but d id not alter the pressure stability of PPO. Benzoic acid protected the enzyme toward temperature but caused sensitization toward pressure wh en used at a concentration of 50 mM. Glutathione produced sensitizatio n to both temperature and pressure. It is suggested that the sensitizi ng effect of glutathione is due to an interaction with a disulfide bon d of the enzyme.