Peroxidase activity in roots of arracacha affected by pH and temperature

Abstract

In this paper, roots of arracacha (Arracacia xanthorrhyza Bancroft) were stored at 5°C to induce chilling injury symptoms and stress-related peroxidase activity. Later, peroxidase kinetic activity was determined in different pH and temperature conditions. For this, soluble crude extract was sequentially saturated with ammonium sulfate, obtaining a semi-purified enzyme solution used for the analysis. Activity of peroxidase induced by the chilling at 5°C was determined from pH 2.5 to 9.0 and at temperature ranging from 10 to 80°C. The peroxidase had higher activity when the reaction occurred between pH 5.5 and 6.0 and at temperature of 30°C. Complete inactivation of the activity was observed in pH 2.5 after 60 minutes of pre-incubation or at 60°C for 10 minutes or alternatively at 70°C after 5 minutes of pre-incubation. The enzyme is more susceptible to inactivation in acid than alkaline pHs or alternatively using heat treatment.