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Latent polyphenol oxidase from quince fruit pulp ( Cydonia oblonga ): purification, activation and some properties
Author(s) -
OrenesPiñero Esteban,
GarcíaCarmona Francisco,
SánchezFerrer Alvaro
Publication year - 2006
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2593
Subject(s) - chemistry , polyphenol oxidase , tropolone , browning , catechol oxidase , sodium dodecyl sulfate , enzyme , chromatography , phosphate , pulp (tooth) , ammonium sulfate , nuclear chemistry , oxidizing agent , ammonium , organic chemistry , biochemistry , medicine , peroxidase , pathology
Quince fruit polyphenol oxidase (PPO) was partially purified using a combination of phase partitioning in Triton X‐114 and PEG 8000/phosphate with a final ammonium sulfate fractionation between 30% and 75%, to avoid the deep browning of the enzyme due to the high amount of oxidizing substances present in the quince pulp. The clean and stable enzyme was partially purified in a latent form and could be optimally activated by the presence of 0.5 g dm −3 sodium dodecyl sulfate (SDS) with an optimum pH of 5.0. In the absence of SDS, the enzyme showed maximum activity at acid pH. The apparent kinetic parameters of the latent enzyme were determined at pH 5.0, the V m value being 15 times higher in the presence of SDS than in its absence, whereas the K M was the same in both cases, with a value of 1.2 mmol L −1 . The effect of several inhibitors was studied, tropolone being the most active with a K i value of 4.7 µmol L −1 . In addition, the effect of cyclodextrins was studied, and the complexation constant ( K c ) between 4‐ tert ‐butylcatechol and cyclodextrins was calculated using an enzymatic method. The value obtained for K c was 15 310 mol L −1 . Copyright © 2006 Society of Chemical Industry