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PURIFICATION AND CHARACTERIZATION OF POLYPHENOL OXIDASE FROM POTATO: I. PURIFICATION AND PROPERTIES
Author(s) -
CHO YONG K.,
AHN HYE K.
Publication year - 1999
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1999.tb00587.x
Subject(s) - catechol , pyrogallol , chemistry , polyphenol oxidase , caffeic acid , sephadex , catechol oxidase , chromatography , enzyme , size exclusion chromatography , enzyme assay , chlorogenic acid , tropolone , tyrosinase , ammonium sulfate , biochemistry , organic chemistry , antioxidant , peroxidase
Polyphenol oxidase (Isozyme I) from potato was extracted and purified with ammonium sulfate, cation‐exchange (Bio‐Rad Bio‐Scale S2) and Sephadex G‐100 column chromatography. The enzyme was purified 11.8 fold resulting in a specific activity of 250.3 units/mg. Optimum pH of the enzyme was 6.6. Optimum temperature of the enzyme was 40C and its half‐life was 0.8 min at 70C. The K m for catechol, pyrogallol, 4‐methyl catechol, caffeic acid and L‐DOPA were 4.11 mM, 0.61 mM, 0.78 mM, 0.50 mM and 32 mM, respectively. However, monophenols such as tyrosine, p‐cresol and 1‐naphtol did not show any activity. Data for V max /K m which represents catalytic efficiency show that 4‐methyl catechol has the highest value. The molecular weight of the active enzyme was 86,000 Da, composed of two identical subunits. The number of Cu 2+ ions bound was found to be 2 per enzyme molecule.