Results 281 to 290 of about 61,180 (326)

Polyphenol Oxidase from Allium sp.

Journal of Agricultural and Food Chemistry, 1997
Polyphenol oxidase (PPO) was isolated from Allium sp. PPO showed activity to catechol and dl-dopa (Km values were 25 mM for cathecol and 33 mM for dl-dopa;Vmax values were 666 EU/mL·min for cathecol and 166 EU/mL·min for dl-dopa). Catechol was the most suitable substrate for Allium sp. PPO (lowest Km value).
Tozlu, I, Arslan, O, Temur, A
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Characterization of polyphenol oxidase in coffee

Phytochemistry, 2000
Polyphenol oxidase (PPO) was characterized in partially purified extracts of leaves (PPO-L) and fruit endosperm (PPO-E) of coffee (Coffea arabica L.). PPO activity was higher in early developmental stages of both leaves and endosperm of fruits. Wounding or exposure of coffee leaves to methyl jasmonate increased PPO activity 1.5-4-fold.
P, Mazzafera, S P, Robinson
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Recombinant polyphenol oxidases for production of theaflavins from tea polyphenols

International Journal of Biological Macromolecules, 2019
Theaflavins (TFs) have attracted much attention due to their various bioactivities in black tea. This paper describes the first trial for enzymatic production of TFs by recombinant polyphenol oxidases (PPOs). PPO genes were cloned from nine species and expressed in E. coli.
Jun, Zeng, Gang, Du, Xue, Shao, Ke-Na, Feng, Ying, Zeng   +4 more
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New Spectrophotometric Assay for Polyphenol Oxidase Activity

Analytical Biochemistry, 1993
We describe a convenient and sensitive assay of polyphenol oxidase (PPO, EC 1.14.18.1) consisting of spectrophotometry at 300 nm based on the stoichiometric reaction of cysteine with o-quinones produced during the enzymatic oxidation of phenols. The adduct formed exhibited spectral properties different from those of the parent phenol.
Gauillard, Frederic, Forget, Florence, Nicolas, J.   +2 more
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Polyphenol Oxidase‐Like Nanozymes

Advanced Materials
Abstract Nanozymes are nanomaterials with enzyme‐like activities. Over the past decade, a steadily growing body of research on polyphenol oxidase‐like (PPO‐like) nanozymes, a subgroup of oxidase‐like nanozymes, has suggested their increasing prominence in nanozymology. Most importantly, PPO‐like nanozymes have developed a unique, well‐
Haolun Gu, Jingqi Li, Pengyu Dai, Tiedong Sun, Chunxia Chen, Zhong Guo, Kelong Fan   +6 more
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Isoenzymes of banana polyphenol oxidase

Phytochemistry, 1975
Abstract Polyacrylamide-gel electrophoresis revealed 9 polyphenol oxidase (PPO) isoenzymes in the interior of banana pulp, 8 in the exterior pulp, and 10 in the peel. With the exception of the absence of one isoenzyme in the exterior pulp, the isoenzymes in the exterior and interior pulp had similar relative mobilities ( R m ).
M.W. Montgomery, V.C. Sgarbieri
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Polyphenol Oxidase, Beyond Enzyme Browning

2018
Enzyme browning is a usual phenomenon that can be observed commonly in fruits and vegetables, which results in quality loss of the food including the change in color, taste, flavor, and nutritional value. This occurs when the phenolic compounds present in them react with polyphenol oxidase (type III copper enzyme).
E. Selvarajan, R. Veena, N. Manoj Kumar
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Preharvest changes in polyphenols, peroxidase, and polyphenol oxidase in sorghum grain

Journal of Agricultural and Food Chemistry, 1981
At various stages of preharvest development. "bird-resistant" sorghum (Sorghum bicolor (I,.) Moench] grain was analyzed for tannin content and polyphenol oxidizing enzymes. Tannins appeared first at the milk stage, reached a maximum at the hard dough stage, and thereafter declined by 25%. Polyphenol oxidase (PPO) and peroxidase activities were detected
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Direct Electrochemistry of Polyphenol Oxidase

2014
The electrochemistry of banana tissues on a carbon paste electrode modified with multi-walled carbon nanotubes (MWCNTs) is presented. Cyclic voltammetry is applied to investigate the direct electrochemistry of banana tissues i.e. a source of polyphenol oxidase (PPO). A redox couple with an anodic and counterpart cathodic peak is obtained. The influence
Raoof, Jahan Bakhsh, Kiani, Abolfazl, Ojani, Reza, Valiollahi, Roudabeh   +3 more
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[145] Plant tyrosinase (polyphenol oxidase)

1955
Publisher Summary This chapter discusses the determination plant tyrosinase. The darkening of mushrooms, potatoes, apples, and many other plants and plant products on injury to the tissue is the result of the enzymatic oxidation of certain mo/aohydric and o-dihydric phenols.
Charles R. Dawson, Richard J. Magee
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