Current applications of peroxidase in various areas of biotechnology and clinical biochemistry show the interest for further screening for peroxidase. Thus, peroxidase activities were screened in higher plants such as Allium sativum, Ipomoea batatas, Raphanus sativus and Sorghum bicolor grown in a tropical environment. The enzymes were investigated for their specific activities and best physicochemical conditions for activity and stabilities. Optima conditions with respect to pH, temperature and their heat inactivation were determined by monitoring the hydrogen peroxide-dependant oxidation of guaiacol. Results revealed that peroxidase specific activities in R. sativus were higher than the other three plant species. Optimum pHs of all screened peroxidase activities were in the acidic range (pH 4.5 to 6.5). Optimum temperatures were ranging from 30 to 40°C. Peroxidase from R. sativus was the most
thermostable enzyme among the four plants. This suggests that R. sativus is a good source of plant peroxidase, which could be used for various applications.

Allium sativum Ipomoea batatas Raphanus sativus Sorghum bicolor