LIPOXYGENASE INACTIVATION BY MANOTHERMOSONICATION - EFFECTS OF SONICATION PHYSICAL PARAMETERS, PH, KCL, SUGARS, GLYCEROL, AND ENZYME CONCENTRATION

Manothermosonication (MTS) efficiency in lipoxygenase (LOX) inactivation, in phosphate buffer, pH 6.5, increases with ultrasound amplitude in the range 0-104 mu m at any temperature from 67.5 to 76.3 degrees C. Activation energy (E(a)) is lower in MTS than in thermal enzyme inactivation and decreases with increasing ultrasound amplitude. Thermal and MTS resistance of the enzyme raises with decreasing pH in the range 5.2-8, but more so thermal than MTS resistance. Differences of E(a) between thermal and MTS enzyme inactivation increase with decreasing pH. Glucose, sucrose, and glycerol increase both thermal and MTS LOX resistance. Neither of these enzyme stabilizers deviates the MTS inactivation course from first-order kinetics but all of them transform in biphasic the thermal inactivation course. LOX concentration does not affect thermal stability but increasing concentration of the enzyme increases MTS resistance. These results are discussed in terms of the possible inactivation mechanism added to heat by ultrasonic waves in MTS.