Soybean lipoxygenase inactivation by pressure at subzero and elevated temperatures.
Soybean lipoxygenase (LOX) inactivation [0.4 mg/mL in Tris-HCl buffer (0.01 M, pH 9)] was studied quantitatively under constant pressure (up to 650 MPa) and temperature (-15 to 68 degrees C) conditions and kinetically characterized by rate constants, activation energies, and activation volumes. The irreversible LOX inactivation followed a first-order reaction at all pressure-temperature combinations tested. In the entire pressure-temperature area studied, LOX inactivation rate constants increased with increasing pressure at constant temperature. On the contrary, at constant pressure, the inactivation rate constants showed a minimum around 30 degrees C and could be increased by either a temperature increase or decrease. On the basis of the calculated rate constants at 102 pressure-temperature combinations, an iso-rate contour diagram was constructed as a function of pressure and temperature. The pressure-temperature dependence of the LOX inactivation rate constants was described successfully using a modified kinetic model of Hawley.
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Department of Food and Microbial Technology, Laboratory of Food Technology, Katholieke Universiteit te Leuven, Heverlee, Belgium.
Van Loey
A M
AM
Ludikhuyze
L R
LR
Hendrickx
M E
ME
D005615:Freezing; D007700:Kinetics; D008084:Lipoxygenase / Q000378:metabolism*; D011312:Pressure; D013025:Glycine max / Q000201:enzymology*; D013816:Thermodynamics
D008084:Lipoxygenase