Plant polyphenol oxidases: isolation and characterization

Abstract

Polyphenol oxidases are found both in prokaryotic and eukaryotic microorganisms, in mammals, invertebrates and plants. Most plants have multiple forms of PPO. The more recent articles regarding the polyphenol oxidases from different plants are reviewed. The main characteristics considered were the sources, structure and properties of polyphenol oxidase (PPO) as well as the inhibitors of this enzyme. The polyphenol oxidase was extracted and purified from different plants such as parsley, banana, grapes, durum wheat, etc and it was achieved a fold purification in the range 3.32 – 259 with a recovery between 5.11 – 44.3% The optimum pH and temperature for polyphenol oxidases from various sources of plants were in the range of 4.0 – 8.5 and 30ºC - 80ºC. The affinity of the enzyme varied depending on the substrate used, thus the polyphenol oxidases from plants had the highest affinity for 4-methylcatechol, catechol and pyrogallol. For the inhibition studies, there were tested many substances but the most effective inhibitors for almost every PPO were: ascorbic acid, citric acid, L-cysteine and sodium metabisulfite.