title: Soybean lipoxygenase inactivation by pressure at subzero and elevated temperatures.
abstract: 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.
authors.affiliation: Department of Food and Microbial Technology, Laboratory of Food Technology, Katholieke Universiteit te Leuven, Heverlee, Belgium.
authors.forename: I
authors.initials: I
authors.lastname: Indrawati
authors.forename: A M
authors.initials: AM
authors.lastname: Van Loey
authors.forename: L R
authors.initials: LR
authors.lastname: Ludikhuyze
authors.forename: M E
authors.initials: ME
authors.lastname: Hendrickx
mesh_terms: D005615:Freezing; D007700:Kinetics; D008084:Lipoxygenase / Q000378:metabolism*; D011312:Pressure; D013025:Glycine max / Q000201:enzymology*; D013816:Thermodynamics
chemical_list: D008084:Lipoxygenase