Polyphenol oxidase is an enzyme found in the chloroplast of plants. Upon cell rupture (when fruit is cut or bruised), it catalyzes the oxidation of phenolic compounds (like tyrosine) to make diphenols and quinones, which polymerize to form compounds that result in brown color development. These reactions are also involved in the formation of melanin, the brown pigment in skin. Since tyrosine is a substrate, the enzyme is sometimes referred to as Tyrosinase. This page will focus on the plant polyphenol oxidases.
Structural highlights
Polyphenol oxidase uses copper to catalyze
