Results 231 to 240 of about 34,133 (279)

Amperometric catechol biosensor based on polyaniline–polyphenol oxidase

Biosensors and Bioelectronics, 2010
A novel catechol biosensor was described based on the immobilization of polyphenol oxidase (PPO) into polyaniline (PANI), which was easily constructed by direct electropolymerization of aniline in a solution containing ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES).
Yongyan, Tan, Xiaoxia, Guo, Jinghui, Zhang, Jinqing, Kan   +3 more
openaire   +2 more sources

Platinum Nanoparticles: Efficient and Stable Catechol Oxidase Mimetics

ACS Applied Materials & Interfaces, 2015
Although enzyme-like nanomaterials have been extensively investigated over the past decade, most research has focused on the peroxidase-like, catalase-like, or SOD-like activity of these nanomaterials. Identifying nanomaterials having oxidase-like activities has received less attention. In this study, we demonstrate that platinum nanoparticles (Pt NPs)
Yi, Liu, Haohao, Wu, Yu, Chong, Wayne G, Wamer, Qingsu, Xia, Lining, Cai, Zhihong, Nie, Peter P, Fu, Jun-Jie, Yin   +8 more
openaire   +2 more sources

Catechol oxidase of red delicious apple peel

Phytochemistry, 1972
Abstract Catechol oxidase has been solubilized from the particulate fraction of apple peel using Triton X-100, dialysis and butanol extraction. The partially purified enzyme retained activity during lyophilization in the presence of mercaptobenzothiazole. The substrate specificity and pH optima of the enzyme are reported.
David A. Stelzig, S. Akhtar, S. Ribeiro
openaire   +1 more source

The catalytic cycle of catechol oxidase

JBIC Journal of Biological Inorganic Chemistry, 2004
Hybrid density functional theory with the B3LYP functional has been used to investigate the catalytic mechanism of catechol oxidase. Catechol oxidase belongs to a class of enzymes that has a copper dimer with histidine ligands at the active site. Another member of this class is tyrosinase, which has been studied by similar methods previously.
openaire   +2 more sources

Multiple forms of Vitis vinifera catechol oxidase

Phytochemistry, 1973
Abstract Grape catechol oxidase shows multiple forms upon ion exchange chromatography, acrylamide gel electrophoresis and gel filtration. Conversion of some bands into others, which occurs during isolation and storage, is enhanced by dilution and by treatment with urea or acid pH.
Eitan Harel, Alfred M. Mayer, Eliakim Lehman   +2 more
openaire   +1 more source

Tyrosinase versus Catechol Oxidase: One Asparagine Makes the Difference

Angewandte Chemie International Edition, 2016
AbstractTyrosinases mediate the ortho‐hydroxylation and two‐electron oxidation of monophenols to ortho‐quinones. Catechol oxidases only catalyze the oxidation of diphenols. Although it is of significant interest, the origin of the functional discrimination between tyrosinases and catechol oxidases has been unclear. Recently, it has been postulated that
Even, Solem, Felix, Tuczek, Heinz, Decker   +2 more
openaire   +2 more sources

Theoretical study of the catalytic mechanism of catechol oxidase

JBIC Journal of Biological Inorganic Chemistry, 2007
The mechanism for the oxidation of catechol by catechol oxidase has been studied using B3LYP hybrid density functional theory. On the basis of the X-ray structure of the enzyme, the molecular system investigated includes the first-shell protein ligands of the two metal centers as well as the second-shell ligand Cys92.
Mireia, Güell, Per E M, Siegbahn
openaire   +2 more sources

Catechol oxidases, endogenous substrates and browning in developing apples

Journal of the Science of Food and Agriculture, 1966
AbstractThe content of o‐diphenols and catechol oxidase activity was followed in developing apples from fruit set to harvest time. Afterwards their level drops, apparently due to conversion to other compounds and cessation of synthesis. Catechol oxidase activity shows a peak after that occurring in content of o‐diphenols.
E, Harel, A M, Mayer, Y, Shain
openaire   +2 more sources

Zero‐Order Catechol Oxidase Activity by a Mononuclear Manganese(III) Complex Showing High Turnover Comparable to Catechol Oxidase Enzyme

ChemCatChem, 2013
Enzymatic mimics are designed by using small molecules to impart insight into the mechanistic pathways of the enzymes and to generate catalysts that could be as efficient as the enzyme itself. Among the copper-based polyphenol oxidase enzymes, the copper(II)-containing enzyme catechol oxidase catalyses exclusively the oxidation of ortho-diphenols to ...
Suman Kr Dey, Arindam Mukherjee
openaire   +1 more source

Evidence for conformational changes in grape catechol oxidase

Phytochemistry, 1972
Abstract A rapid, 4–10-fold, activation of grape catechol oxidase by a short exposure to acid pH or urea is demonstrated. Activation was either reversible or irreversible, depending on length and type of treatment. The change in activity of the enzyme is due primarily to an increase in V max , while the affinity for 4-methylcatechol decreases and ...
H.R. Lerner, A.M. Mayer, E. Harel
openaire   +1 more source