High pressure and thermal denaturation kinetics of soybean lipoxygenase: astudy based on gel electrophoresis

Gel electrophoresis was used to verify the physicochemical characteristics of the commercially available soybean lipoxygenase. The sample was characte rized by a molar mass of 92 700 +/- 1500 g/mol and two isozymes wee detecte d, characterized by isoelectric points of 5.71 +/- 0.06 and 5.09 +/- 0.02 r espectively. Gel electrophoresis was then used to analyze the denaturation kinetics of lipoxygenase. Both thermal and pressure denaturation could be a ccurately described by a first order kinetic model. The kinetic parameters describing denaturation (as determined by changes in native conformation, m easured using gel electrophoresis) were not in agreement with those describ ing inactivation (as determined by spectrophotometrically measured changes in residual activity). In general, inactivation seemed to occur more readil y than denaturation, indicating that only minor changes in the tertiary str ucture are responsible for the loss of enzyme activity.