出典:Wiktionary
polyphenoloxidase (複数形 polyphenoloxidases)
出典:Wikipedia
出典:『Wikipedia』 (2011/01/13 19:37 UTC 版)
Polyphenol oxidase (PPO or monophenol monooxygenase) enzymes catalyse 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). They can also further catalyse the oxidation of o-diphenols to produce o-quinones. It is the rapid polymerisation of o-quinones to produce black, brown or red pigments (polyphenols) that is the cause of fruit browning. The amino acid tyrosine contains a single phenolic ring that may be oxidised by the action of PPOs to form o-quinone. Hence, PPOs may also be referred to as tyrosinases.