Engenharia Enzimática
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Polyphonel Oxidases: Biochemical and Molecular Characterization, Distribution, Role and its Control

Bibhuti Bhusan Mishra and Satyendra Gautam*

The polyphenol oxidase (PPO) catalyzes oxidation of phenolics and responsible for enzymatic browning in plant products, seafood, and melanin formation in skin. The enzyme has been reported to be universally distributed in animals, plants, fungi and bacteria. It has received significant attention from researchers due to its involvement in the post-processing enzymatic browning i.e. a major problem for various food industries particularly dealing with cut fruits and vegetables and juices. The enzymes purified form different plant sources showed differences in the biochemical characteristics. The PPO protein structure has been solved and reported in few plants. The enzyme is a copper protein. The actice site of the enzyme undergoes transitions among met-, oxy-, and deoxy-forms in a cyclic manner for catalysis. The gene sequences from different sources show homology among close family members and introns are peculiary found to be absent in many cases. Various physical, chemical, and genetic methods have been proposed for inhibiting or preventing PPO activity for the control of undesirable enzyme activity, and also to achieve disease resitance in certain cases. The current review aims to consolidate the understandings about the PPO enzyme and possible means of its control.