• Enzymes like monoamine oxidase (MAO) can oxidize dopamine, leading to the formation of reactive intermediates such as quinones and reactive oxygen species. (thesciencenotes.com)
  • However, semiquinone intermediates produced during the one-electron reduction of these compounds, as well as through auto-oxidation of the hydroxyquinone product, generate reactive oxygen species that stress the cell. (rhea-db.org)
  • Modulator of drug activity B is reported to be involved in the protection of cells from reactive oxygen species formed during single electron oxidation and reduction reactions. (rhea-db.org)
  • DA is unstable and can undergo oxidation and metabolism to produce multiple reactive and toxic by-products, including reactive oxygen species, DA quinones, and 3,4-dihydroxyphenylacetaldehyde. (biomedcentral.com)
  • The effects of sulforaphane on multiple pathways of biochemical dysfunction, increased reactive oxygen species (ROS) formation, hexosamine pathway, protein kinase C (PKC) pathway, and increased formation of methylglyoxal were assessed. (diabetesjournals.org)
  • 48], Superoxide is a reactive oxygen species that contributes to cellular oxidative stress and is linked to neuromuscular diseases and aging. (gowebamerica.com)
  • It is also a major contributor to cellular production of reactive oxygen species. (gowebamerica.com)
  • Reactive oxygen species are reactive molecules that play a role in cellular signaling and are formed as side products in physiological processes. (5dok.net)
  • Many external factors are implicated with carcinogenesis, one of which are reactive oxygen species. (5dok.net)
  • Alcohol dehydrogenase (ADH) contributes significantly to NADH-dependent C-nitroso reduction by cytosol relative to NAD(P)H: quinone oxidoreductase (NQOR). (lsu.edu)
  • NAD(P)H:quinone acceptor oxidoreductase 1 (NQO1) is a widely-distributed FAD-dependent flavoprotein that promotes obligatory 2-electron reductions of quinones, quinoneimines, nitroaromatics, and azo dyes, at rates that are comparable with NADH or NADPH. (dundee.ac.uk)
  • These partially ionized gases deliver a therapeutic cocktail of reactive oxygen and nitrogen species safely at body temperature and without genotoxic side effects. (mdpi.com)
  • For example, they imaged the protonation/deprotonation state (related to the pH) of sites within the enzyme that are important for stabilizing radical species (i.e., especially reactive atoms that contain an unpaired electron). (sciencedaily.com)
  • NA metabolism results in the generation of reactive intermediates such as 1,2-epoxide and reactive metabolites such as 1,4- and 1,2- naphthoquinone (NAQ). (nih.gov)
  • Reactive quinone and epoxide metabolites of similar compounds, such as benzo[a]pyrene, have been shown to enact their carcinogenecity through DNA adduct formation. (nih.gov)
  • Graduate research activities involving mechanistic studies on xenobiotic toxicity invariably expose students to the field of drug metabolism, particularly in cases where xenobiotics are enzymatically bioactivated to electrophilic reactive metabolites that can covalently adduct to proteins and DNA and cause toxicity. (aspetjournals.org)
  • Structural and biochemical evidence for an enzymatic quinone redox cycle in Escherichia coli: identification of a novel quinol monooxygenase. (rhea-db.org)
  • The enzymatic activities, together with the structural characterization of YgiN, lend evidence to the possible existence of a novel quinone redox cycle in E. coli. (rhea-db.org)
  • 12][13], The equilibrium dynamics of Complex I are primarily driven by the quinone redox cycle. (gowebamerica.com)
  • DFs release the quinone imine and free H2 O2 in the oxidation of 4-aminophenol in the presence of O2 , whereas Fe(III) -DF-C1 sequesters the quinone imine into the active site, and catalyzes inside the scaffold an oxidative coupling between oxidized and reduced 4-aminophenol. (cnr.it)
  • Despite the unprecedented variability of chemical reactions catalyzed by cytochromes P450, all the important features of their mechanism can be attributed to the oxidative transformations driven by the main catalytic intermediate, which is a ferryl-oxo heme complex with the porphyrin pi-cation radical, or Compound I (3, 4, 8). (schoolbag.info)
  • As a result, only a pyrimidine analog of NVP, which could avoid the formation of a reactive epoxide intermediate, did not inhibit CYP3A4. (unboundmedicine.com)
  • These results indicated that the epoxide intermediate of NVP might play an important role in NVP-induced liver injury. (unboundmedicine.com)
  • Outside of this compound, the other synthesized compounds, which could avoid the generation of a reactive quinone-methide intermediate, inhibited CYP3A4 equal to or stronger than NVP. (unboundmedicine.com)
  • C-nitroso compounds are reactive intermediates in the toxic sequelae of nitroarene metabolism. (lsu.edu)
  • The structural aspects and important functional groups of several classes of molecules that have been found to impart mechanism-based inactivation upon metabolism by P450s such as acetylenes, thiol-containing compounds that include isothiocyanates, thiazolidinediones, and thiophenes, arylamines, quinones, furanocoumarins, and cyclic tertiary amines are described. (johnshopkins.edu)
  • Originally discovered by Sodeoka 25 years ago, they readily form reactive chiral Pd enolates upon deprotonation of b-dicarbonyl compounds and simultaneously, a Brønsted acid liberated from the catalyst activates the electrophile. (uni-leipzig.de)
  • We previously reported the utility of a nitrobenzenethiol (NBT) binding assay for screening thiol reactive haptens (Chipinda et al Chem. (cdc.gov)
  • Cytochrome P450 1B1 (CYP1B1) is active in the metabolism of estrogens to reactive catechols and of different procarcinogens. (biomedcentral.com)
  • Suwannee River fulvic acid (SRFA) as a model DOM was pre-oxidised using the phenol-reactive oxidants chlorine and ozone, followed by its characterization by the specific UV absorption at 254 nm (SUVA 254 ), the ratio of absorbance at λ = 254 nm and λ = 365 nm (E2:E3), and the electron donating capacity (EDC). (eawag.ch)
  • Whereas there remains much to learn about the potential biological relevance of UGTs, deficient glucuronidation can result in either elevated tissue concentrations and direct toxicity of substrates, as with the endobiotic bilirubin, or, alternatively, enhanced bioactivation of substrates to toxic reactive intermediates, as in the case of acetaminophen and benzo[ a ]pyrene. (aspetjournals.org)
  • Cytochromes P450 monooxygenases represent a large superfamily of heme enzymes, which require a dioxygen molecule and two electrons supplied by a NAD(P)H-dependent protein redox partner to form catalytically active high-valent ferryl-oxo intermediate. (schoolbag.info)
  • Cytochromes P450 represent a superfamily of heme enzymes with a common fold and mechanism that requires an atmospheric dioxygen molecule, two electrons from NAD(P)H, and one or two protons available from solvent water to form an active catalytic ferryl-oxo intermediate (1). (schoolbag.info)
  • Most reactions performed by cytochromes P450 can be catalyzed effectively by Compound I, which is formally the same high-valent intermediate in all isozymes (5, 6). (schoolbag.info)
  • After the primary coupling of two phenoxy radicals a very reactive quinone methide intermediate is formed. (vtt.fi)
  • Recent studies suggested that long-lived photooxidants (LLPO), which are reactive intermediates formed during irradiation of dissolved organic matter (DOM), may consist of phenoxyl radicals derived from phenolic moieties of the DOM. (eawag.ch)
  • These reductions depress quinone levels and thereby minimize opportunities for generation of reactive oxygen intermediates by redox cycling, and for depletion of intracellular thiol pools. (dundee.ac.uk)
  • Although P450-catalyzed reactions are generally thought to lead to detoxication of xenobiotics, the reactions can also produce reactive intermediates that can react with cellular macromolecules leading to toxicity or that can react with the P450s that form them leading to irreversible (i.e., mechanism-based) inactivation. (johnshopkins.edu)
  • Naturally synthesized quinones perform a variety of important cellular functions. (rhea-db.org)
  • It is formed as an intermediate during the formation of norepinephrine and epinephrine [ 20 ]. (biomedcentral.com)
  • Second protonation of the distal oxygen atom and transient formation of the iron coordinated oxo-water, Fe-OOH 2 , results in the heterolytic scission of O-O bond and formation of the ferryl oxo porphyrin-cation radical, which is termed Compound I, by analogy to the same active intermediate first documented in peroxidases and catalases (2). (schoolbag.info)
  • Indeed, organic azides, particularly in the aliphatic series, are exceptionally stable toward the common reactive chemicals, ranging from dioxygen and water to the aqueous solutions of highly-functionalized organic molecules which make up living cells. (justia.com)
  • The iron serves as a sole redox center in the catalytic cycle, which accepts two electrons sequentially and channels them to coordinated dioxygen to form a (hydro)peroxo-ferric intermediate. (schoolbag.info)
  • Preliminary assessment suggests labile reactive intermediates are formed during PDA reaction to quinones and benzyl bromide. (cdc.gov)
  • This intermediate reacts quickly with a suitable nucleophile which can be, for example, an intramolecular hydroxyl group or another nucleophile such as water, methanol, or a phenolic compound in the reaction system. (vtt.fi)
  • Emphasis throughout this perspective is placed on more recent findings with human P450s where the site of modification, whether it be the apoprotein or the heme moiety, and, at least in part, the identity of the reactive intermediate responsible for the loss in P450 activity are known or inferred. (johnshopkins.edu)
  • There are pH-dependence, conformational change, and radical intermediate stabilization questions of our enzyme that X-ray crystallography in itself cannot fully explain," explains Takeshi Murakawa, lead author of the study. (sciencedaily.com)
  • 14], The coupling of proton translocation and electron transport in Complex I is currently proposed as being indirect (long range conformational changes) as opposed to direct (redox intermediates in the hydrogen pumps as in heme groups of Complexes III and IV). (gowebamerica.com)
  • Substrate binding at the distal site of the heme brings the target chemical group into the close proximity of the reactive iron-oxygen catalytic intermediate, often in the regiospecific and stereospecific mode, to provide the selectivity of the chemical transformation. (schoolbag.info)
  • Recent advances in trapping procedures as well as new methods for identification of reactive intermediates are presented. (johnshopkins.edu)
  • Among these, the citric acid cycle intermediate succinate stands out owing to its multiple roles in disparate pathways, its dramatic concentration changes and its selective cell release. (nature.com)
  • The azide intermediate is shown in brackets because it is generally reduced straightaway to the amine. (justia.com)