The inactivation kinetics of horseradish peroxidase (HRP) heated in capillary tubes in the range 110 to 135°C was studied. Its regeneration kinetics when stored at 4 and 25°C was also considered. As the severity of the treatment increased, the absolute value of the regeneration decreased. The storage temperature of the enzyme did not affect the percentage of maximum activity regenerable, although when this temperature was raised from 4 to 25°C the speed of regeneration increased. Kinetics of HRP inactivation determined after heating and after regeneration were compared. Both forms of the enzyme showed similar behavior with first-order inactivation kinetics, with Ea = 19.5 ± 1.0 kcal/mol and k120°C = 3.7 ± 0.2 min-1, and Ea = 18.8 ± 1.2 kcal/mol and k120°C = 3.7 ± 0.2 min-1, respectively.
Keywords: HTST; Horseradish peroxidase; enzyme kinetics; enzyme regeneration; thermal inactivation.