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Cherimoya ( Annona cherimola Mill) Polyphenoloxidase: Monophenolase and Dihydroxyphenolase Activities
Author(s) -
MARTINEZCAYUELA MARINA,
MEDINA LUIS SANCHEZ,
FAUS MARIA JOSE,
GIL ANGEL
Publication year - 1988
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1988.tb13559.x
Subject(s) - chemistry , hydroxylation , ascorbic acid , catechol , catechol oxidase , tyramine , food science , organic chemistry , biochemistry , enzyme , polyphenol oxidase , peroxidase
Polyphenoloxidase (PPO) from cherimoya epicarp catalyzed the hydroxylation of monphenols like L(−)tyrosine, tyramine, and p‐cresol (monophenolase activity), and oxidation of o‐dihydroxyphenols like catechol and L‐DOPA (dihydroxyphenolase activity). The hydroxylation of monophenols occurred after a lag period which was shortened by diphenols. The Km values indicated a low affinity of PPO to the substrates. Aliphatic mono‐ and dicarboxylic acids and sugars did not show any inhibitory effect on PPO cherimoya epicarp. Cysteine and mercaptoethanol, but not ascorbic acid, appeared to be protective agents of PPO cherimoya epicarp.