Tags: Enzyme.
Polyphenol oxidase (PPO or monophenol monooxygenase or Polyphenol oxidase I chloroplastic) is a tetramer that contains four atoms of copper per molecule and binding sites for two aromatic compounds and oxygen. The enzyme catalyses the o-hydroxylation of monophenols (phenol molecules in which the benzene ring contains a single hydroxyl substituent) to o-diphenols (phenol molecules containing two hydroxyl substituents).