Premium
Partial purification and characterisation of polyphenol oxidase from celery root ( Apium graveolens L.) and the investigation of the effects on the enzyme activity of some inhibitors
Author(s) -
Aydemir Tülin,
Akkanlı Gülay
Publication year - 2006
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2006.01191.x
Subject(s) - chemistry , polyphenol oxidase , pyrogallol , catechol , apium graveolens , catechol oxidase , nuclear chemistry , gallic acid , enzyme , chromatography , sucrose , food science , biochemistry , horticulture , antioxidant , peroxidase , biology
Summary Polyphenol oxidase (PPO) of celery root was extracted and partially purified by (NH 4 ) 2 SO 4 fractionation and dialysis. Optimum pH and temperature were found at pH 7.0 and 30 °C, and K m and V max values were 29 m m and 5560 U mL −1 min −1 with catechol, respectively. The activation energy of the enzyme with catechol was 17.9 kJ mol −1 at pH 7.0. In electrophoretic seperation, six isoenzymes were detected with dl ‐dopa substrate. PPO showed activity to catechol, 4‐methylcatechol, pyrogallol, gallic acid, dl ‐dopa. l ‐Tyrosine was also tested but was not oxidised by celery root PPO. β ‐Mercaptoethanol was found to be the most effective inhibitor. (NH 4 ) 2 SO 4 , NaCl, KCl and sucrose appeared to be protective agents of celery root PPO against thermal denaturation. Metal ions (Cu 2+ , Zn 2+ , Mn 2+ ) were poor inhibitors of the celery root PPO at 1 m m . PPO activity was also inhibited by CaCl 2 , NaCl, BaCl 2 , FeSO 4 and NiCl 2 .