Strawberry Polyphenoloxidase: Extraction and Partial Characterization

Autor:	Pedro Wesche-Ebeling, Morris W. Montgomery
Rok vydání:	1990
Předmět:	Potassium metabisulfite Chromatography biology Extraction (chemistry) Substrate (chemistry) Amberlite Ascorbic acid chemistry.chemical_compound Pyrogallol chemistry Browning biology.protein Catechol oxidase Food Science
Zdroj:	Journal of Food Science. 55:1320-1324
ISSN:	1750-3841 0022-1147
DOI:	10.1111/j.1365-2621.1990.tb03925.x
Popis:	Mixing strawberries ground under liquid nitrogen with polyvinylpyrrolidone alone or combined with Amberlite XAD-4 in pH 4.5 buffer yielded stable polyphenoloxidase (PPO) extracts. Temperature stability of the enzyme varied with substrate and followed first order kinetics of inactivation. pH optima were 5.5 with catchol and 4.5 with 4-methylcatechol. Maximum activity was with D-catechin, followed by 4-methylcatechol and pyrogallol with no cresolase activity. Inhibition occurred with diethyldithiocarbamate, potassium metabisulfite, KCN and dithiothreitol. Benzenesulfinic acid, cysteine and ascorbic acid blocked the browning reaction without enzyme inhibition. Extraction with Dowex AG 2-X8 resulted in browning. No loss in activity after 95 days occurred with quick-frozen fruit stored under nitrogen at -40°C.
Databáze:	OpenAIRE
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