scholarly journals Green tea constituents (-)-epigallocatechin-3-gallate (EGCG) and gallic acid induce topoisomerase I- and topoisomerase II-DNA complexes in cells mediated by pyrogallol-induced hydrogen peroxide

Mutagenesis ◽  
2011 ◽  
Vol 26 (4) ◽  
pp. 489-498 ◽  
Author(s):  
M. Lopez-Lazaro ◽  
J. M. Calderon-Montano ◽  
E. Burgos-Moron ◽  
C. A. Austin
Keyword(s):  
Hydrogen Peroxide ◽  
Gallic Acid ◽  
Green Tea ◽  
Topoisomerase I ◽  
Topoisomerase Ii ◽  
Dna Complexes ◽  
In Cells

The Coffee Constituent Chlorogenic Acid Induces Cellular DNA Damage and Formation of Topoisomerase I– and II–DNA Complexes in Cells

2012 ◽  
Vol 60 (30) ◽  
pp. 7384-7391 ◽  
Author(s):  
Estefanía Burgos-Morón ◽  
José Manuel Calderón-Montaño ◽  
Manuel Luis Orta ◽  
Nuria Pastor ◽  
Concepción Pérez-Guerrero ◽  
...  
Keyword(s):  
Dna Damage ◽  
Chlorogenic Acid ◽  
Topoisomerase I ◽  
Dna Complexes ◽  
Cellular Dna ◽  
In Cells

scholarly journals Effect of TDP2 on the Level of TOP2-DNA Complexes and SUMOylated TOP2-DNA Complexes

2018 ◽  
Vol 19 (7) ◽  
pp. 2056 ◽  
Author(s):  
Ka Lee ◽  
Rebecca Swan ◽  
Zbyslaw Sondka ◽  
Kay Padget ◽  
Ian Cowell ◽  
...  
Keyword(s):  
Topoisomerase Ii ◽  
K562 Cells ◽  
Strand Break ◽  
Dna Complexes ◽  
Dna Topoisomerase ◽  
Strand Breaks ◽  
Sumo Ligase ◽  
Dna Complex ◽  
In Cells

DNA topoisomerase II (TOP2) activity involves a normally transient double-strand break intermediate in which the enzyme is coupled to DNA via a 5′-phosphotyrosyl bond. However, etoposide and other topoisomerase drugs poison the enzyme by stabilising this enzyme-bridged break, resulting in the accumulation of TOP2-DNA covalent complexes with cytotoxic consequences. The phosphotyrosyl diesterase TDP2 appears to be required for efficient repair of this unusual type of DNA damage and can remove 5′-tyrosine adducts from a double-stranded oligonucleotide substrate. Here, we adapt the trapped in agarose DNA immunostaining (TARDIS) assay to investigate the role of TDP2 in the removal of TOP2-DNA complexes in vitro and in cells. We report that TDP2 alone does not remove TOP2-DNA complexes from genomic DNA in vitro and that depletion of TDP2 in cells does not slow the removal of TOP2-DNA complexes. Thus, if TDP2 is involved in repairing TOP2 adducts, there must be one or more prior steps in which the protein-DNA complex is processed before TDP2 removes the remaining 5′ tyrosine DNA adducts. While this is partly achieved through the degradation of TOP2 adducts by the proteasome, a proteasome-independent mechanism has also been described involving the SUMOylation of TOP2 by the ZATT E3 SUMO ligase. The TARDIS assay was also adapted to measure the effect of TDP2 knockdown on levels of SUMOylated TOP2-DNA complexes, which together with levels of double strand breaks were unaffected in K562 cells following etoposide exposure and proteasomal inhibition.

Сrude Plant Extracts Mediated Polyphenol Oxidation Reactions in the Presence of 3-Methyl-2-Benzothiazolinone Hydrazone for the Determination of Total Polyphenol Content in Beverages

2018 ◽  
Vol 15 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Maria A. Morosanova ◽  
Anton S. Fedorov ◽  
Elena I. Morosanova
Keyword(s):  
Hydrogen Peroxide ◽  
Ferulic Acid ◽  
Gallic Acid ◽  
Caffeic Acid ◽  
Crude Extract ◽  
Reaction Rates ◽  
Green Bean ◽  
Polyphenol Content ◽  
Total Polyphenol ◽  
Total Polyphenol Content

Background: The consumption of antioxidants, including phenolic compounds, is considered important for preventing the oxidative damage diseases and ageing. The total polyphenol content (TPC) is the parameter used to estimate the quality of plant-derived products. Methods: Phenol oxidase activity of green bean (Phaseolus vulgaris) crude extract (in the presence of hydrogen peroxide) and banana (Musa sp.) pulp crude extract has been studied spectrophotometrically using catechol, gallic acid, caffeic acid, ferulic acid, and quercetin as substrates. All studied compounds have been oxidized in the presence of green bean crude extract and hydrogen peroxide; all studied compounds except ferulic acid have been oxidized in the presence of banana pulp crude extract. Michaelis constants (Km) and maximum reaction rates (Vmax) have been determined for oxidation in the presence of green bean crude extract and hydrogen peroxide (Km are 3.8×10-4 M, 1.6×10-3 M, 2.2×10-4 M, 2.3×10-4 M, 1.4×10-4 M and Vmax are 0.046 min-1, 0.102 min-1, 0.185 min-1, 0.053 min-1, 0.041 min-1 for catechol, gallic acid, caffeic acid, ferulic acid, and quercetin, respectively) and for oxidation in the presence of banana pulp crude extract (Km are 1.6×10-3 M, 3.8×10-3 M, 2.2×10-3 M, 4.2×10-4 M and Vmax are 0.058 min-1, 0.025 min-1, 0.027 min-1, 0.015 min-1 for catechol, gallic acid, caffeic acid, and quercetin, respectively). The influence of 3-methyl-2-benzothiazolinone hydrazone (MBTH) on the oxidation reactions kinetics has been studied: Michaelis constants values decrease and maximum reaction rates increase, which contributes to the increase in sensitivity of the determination. Results: Kinetic procedures of Total Polyphenol Content (TPC) determination using crude plants extracts in the presence of MBTH have been proposed (time of analysis is 1 min). For gallic acid (used as a standard for TPC determination) detection limit is 5.3×10-5 M, quantitation limit is 1.8×10-4 M, and linear range is 1.8×10-4 - 1.3×10-3 M for green bean crude extract; detection limit is 2.9×10-5 M, quantitation limit is 9.5×10-5 M, and linear range is 9.5×10-5 - 2.4×10-3 M for banana pulp crude extract. Proposed procedures are characterized by higher interference thresholds for sulfites, ascorbic acid, and citric acid compared to pure enzymes (horseradish peroxidase and mushroom tyrosinase) in the same conditions. Compared with standard Folin-Ciocalteu (FC) method the procedures described in this work are also characterized by less interference and more rapid determination. Conclusion: The procedures have been applied to TPC determination in tea, coffee, and wine samples. The results agree with the FC method for tea and coffee samples and are lower for wine samples, probably, due to sulfites interference.

Salivary hydrogen peroxide produced by holding or chewing green tea in the oral cavity

2007 ◽  
Vol 41 (7) ◽  
pp. 850-853 ◽  
Author(s):  
Joshua D. Lambert ◽  
Seok-Joo Kwon ◽  
Jungil Hong ◽  
Chung S. Yang
Keyword(s):  
Hydrogen Peroxide ◽  
Oral Cavity ◽  
Green Tea

scholarly journals Altered stability of etoposide-induced topoisomerase II-DNA complexes in resistant human leukaemia K562 cells

1994 ◽  
Vol 69 (4) ◽  
pp. 687-697 ◽  
Author(s):  
MK Ritke ◽  
D Roberts ◽  
WP Allan ◽  
J Raymond ◽  
VV Bergoltz ◽  
...  
Keyword(s):  
Topoisomerase Ii ◽  
K562 Cells ◽  
Dna Complexes ◽  
Human Leukaemia

scholarly journals SNAPSwitch: A Molecular Sensor to Quantify the Localization of Proteins, DNA and Nanoparticles in Cells

2019 ◽  
Author(s):  
Laura I FitzGerald ◽  
Luigi Aurelio ◽  
Moore Chen ◽  
Daniel Yuen ◽  
Bim Graham ◽  
...  
Keyword(s):  
Immune Responses ◽  
Intracellular Trafficking ◽  
Live Cells ◽  
Quantitative Detection ◽  
Dna Complexes ◽  
Receptor Signalling ◽  
Fluorescent Markers ◽  
Molecular Sensor ◽  
Protein Nucleic Acid ◽  
In Cells

Intracellular trafficking governs receptor signalling, pathogenesis, immune responses and the cellular fate of nanomedicines. These processes are typically tracked by confocal microscopy, where colocalization of fluorescent markers implies an interaction or co-compartmentalization. However, this type of analysis is inherently low-throughput, is limited by the resolution of microscopy, and can miss fleeting interactions. To address this, we have developed a localization sensor composed of a quenched and attachable SNAP-tag substrate (SNAPSwitch). SNAPSwitch enables quantitative detection of protein, nucleic acid and nanoparticle trafficking to locations of interest within live cells using flow cytometry. Using this approach, we followed the trafficking of DNA complexes travelling from endosomes into the cytosol and to the nucleus. We also show that antibody targeted to the transferrin (CD71) or hyaluronan (CD44) receptor is initially sorted into different compartments following endocytosis. These results demonstrate SNAPSwitch is a high-throughput and broadly applicable tool to quantitatively track the localization of materials in cells.

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