Reactivity of Mono-Meso-Substituted Iron(II) Octaethylporphyrin Complexes with Hydrogen Peroxide in the Absence of Dioxygen. Evidence for Nucleophilic Attack on the Heme

2001 ◽  
Vol 123 (47) ◽  
pp. 11719-11727 ◽  
Author(s):  
Heather Kalish ◽  
Jason E. Camp ◽  
Marcin Stȩpień ◽  
Lechosław Latos-Grażyński ◽  
Alan L. Balch
Keyword(s):  
Hydrogen Peroxide ◽  
Nucleophilic Attack

Hydroxyl free radical production by the reaction of N-methyl-N′-nitro-N-nitrosoguanidine with hydrogen peroxide without exposure to light

1992 ◽  
Vol 70 (3-4) ◽  
pp. 262-268 ◽  
Author(s):  
Tomiko Mikuni ◽  
Masaharu Tatsuta ◽  
Mikiharu Kamachi
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radical ◽  
Nucleophilic Attack ◽  
Peroxynitrous Acid ◽  
Nitrite Ion ◽  
Hydroxyl Free Radical ◽  
Spin Resonance ◽  
Resonance Spin ◽  
Layer Chromatography ◽  
Spin Trapping Technique

We examined hydroxyl free radical (∙OH) production in the mixture of H2O2 and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) without exposure to light using the electron spin resonance spin-trapping technique. When the mixtures were protected from exposure to light, ∙OH was formed at pH 6.5 and above; it was not formed at pH 5.0 and below, consistent with our previous report. The amount of ∙OH trapped depended on the concentrations of MNNG and H2O2 and the pH. Nitrite ion was also detected colorimetrically at pH 6.5 and above, but not detected at pH 5.0 and below in the mixtures without exposure to light. Moreover, its production depended on the concentrations of MNNG and H2O2 and the pH. The formation of N-methyl-N′-nitroguanidine in the mixture at pH 7.8 was confirmed by thin-layer chromatography and melting point. These results suggest that nucleophilic attack by H2O2 on the nitroso nitrogen of MNNG results in the formation of N-methyl-N′-nitroguanidine and peroxynitrous acid, which degrades homolytically to yield ∙OH and nitrogen dioxide, resulting in the production of nitrite ion, at pH 6.5 and above without exposure to light.Key words: N-methyl-N′-nitro-N-nitrosoguanidine, hydrogen peroxide, hydroxyl free radical, peroxynitrous acid.

Sequence-specific cleavage of DNA via nucleophilic attack of hydrogen peroxide, assisted by flp recombinase

Biochemistry ◽  
1993 ◽  
Vol 32 (18) ◽  
pp. 4698-4701 ◽  
Author(s):  
Amy S. Kimball ◽  
Jehee Lee ◽  
Makkuni Jayaram ◽  
Thomas D. Tullius
Keyword(s):  
Hydrogen Peroxide ◽  
Nucleophilic Attack ◽  
Flp Recombinase

scholarly journals From Hydrogen Peroxide-Responsive Boronated Nucleosides Towards Antisense Therapeutics – A Computational Mechanistic Study

2019 ◽  
Vol 92 (2) ◽  
pp. 287-295
Author(s):  
Tana Tandarić ◽  
Lucija Hok ◽  
Robert Vianello
Keyword(s):  
Hydrogen Peroxide ◽  
Genetic Disorders ◽  
Md Simulations ◽  
Chemical Mechanism ◽  
Nucleophilic Attack ◽  
Mechanistic Study ◽  
Stimuli Responsive ◽  
Nucleic Acid Therapeutics ◽  
Promising Tool ◽  
Synthetic Approaches

We used a combination of MD simulations and DFT calculations to reveal the precise chemical mechanism underlying the conversion of boronated nucleosides to natural nucleosides in the presence of hydrogen peroxide, which was recently experimentally demonstrated by Morihiro and Obika et al. (Chem. Sci. 2018, 9, 1112). Our results show that this process is initiated by the H2O2 deprotonation to a base concerted with the nucleophilic attack of the resulting OOH– anion onto the boron atom as the rate-limiting step of the overall transformation. This liberates a free base, followed by the 1,2-rearrangement to the C–OOH– adduct. Lastly, breaking of the O–O bond within the peroxide moiety cleaves the boron–carbon bond, giving boronic acid ester and the matching ketone as the final products. The obtained reaction profiles successfully interpret a much higher conversion rate of the thymine derivative over its guanine analogue, and rationalize why t-Bu-hydroperoxide is hindering the conversion, thus placing both aspects in firm agreement with experiments. The offered insight represents a promising tool for the future synthetic approaches of stimuli-responsive biomolecules, especially chemically caged prodrug-type nucleic acid therapeutics, bearing significant importance due to their application potential in diagnostics and therapy of various genetic disorders.

The reaction of the hexacyanoferrate(III) ion with hydrogen peroxide

1985 ◽  
Vol 63 (4) ◽  
pp. 793-797 ◽  
Author(s):  
Donald R. Eaton ◽  
Marianne Pankratz
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Reaction ◽  
Superoxide Radical ◽  
Catalytic Reactions ◽  
Nucleophilic Attack ◽  
Basic Solution ◽  
Cyanide Ligand ◽  
Kinetics Of

In basic solution hydrogen peroxide reduces the hexacyanoferrate(III) ion to the Fe(II) complex. The stoichiometry and kinetics of this reaction have been examined. Both a stoichiometric reduction and a catalytic reaction leading to decomposition of the hydrogen peroxide occur. The latter is largely, but not completely, photochemical in origin. The data are consistent with the involvement of a common intermediate for the stoichiometric and the thermal catalytic reactions. It is suggested that this intermediate is formed by nucleophilic attack of the hydroperoxide ion or the superoxide radical on the carbon of a cyanide ligand.

Studies on some 1,2,4-dithiazolium salts

1970 ◽  
Vol 48 (13) ◽  
pp. 2142-2145 ◽  
Author(s):  
M. Ahmed ◽  
D. M. McKinnon
Keyword(s):  
Hydrogen Peroxide ◽  
Dimethyl Sulfate ◽  
Nucleophilic Attack ◽  
Peroxide Oxidation ◽  
Hydrogen Peroxide Oxidation

3-Alkylthio-1,2,4-dithiazolium salts are most conveniently made by alkylation of the corresponding 1,2,4-dithiazole-3-thiones by dimethyl sulfate. These salts readily undergo nucleophilic attack by amines in position 3, with loss of a methylthio group. Hydrogen peroxide oxidation, or chlorination, of the thiones gives the corresponding dithiazole-3-ones.

Peroxidase Localization in Hartmanella Trophozoites

1971 ◽  
Vol 29 ◽  
pp. 346-347 ◽  
Author(s):  
George E. Childs ◽  
Joseph H. Miller
Keyword(s):  
Hydrogen Peroxide ◽  
Ultrastructural Localization ◽  
Pathogenic Strain ◽  
Oxidative Enzymes ◽  
Differential Centrifugation ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
The Subject ◽  
Axenic Cultures

Biochemical and differential centrifugation studies have demonstrated that the oxidative enzymes of Acanthamoeba sp. are localized in mitochondria and peroxisomes (microbodies). Although hartmanellid amoebae have been the subject of several electron microscopic studies, peroxisomes have not been described from these organisms or other protozoa. Cytochemical tests employing diaminobenzidine-tetra HCl (DAB) and hydrogen peroxide were used for the ultrastructural localization of peroxidases of trophozoites of Hartmanella sp. (A-l, Culbertson), a pathogenic strain grown in axenic cultures of trypticase soy broth.

Fluorescent proteins for in vivo imaging, where's the biliverdin?

2020 ◽  
Vol 48 (6) ◽  
pp. 2657-2667
Author(s):  
Felipe Montecinos-Franjola ◽  
John Y. Lin ◽  
Erik A. Rodriguez
Keyword(s):  
Hydrogen Peroxide ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Imaging ◽  
Infrared Light ◽  
Red Fluorescent Protein ◽  
Color Palette

Noninvasive fluorescent imaging requires far-red and near-infrared fluorescent proteins for deeper imaging. Near-infrared light penetrates biological tissue with blood vessels due to low absorbance, scattering, and reflection of light and has a greater signal-to-noise due to less autofluorescence. Far-red and near-infrared fluorescent proteins absorb light >600 nm to expand the color palette for imaging multiple biosensors and noninvasive in vivo imaging. The ideal fluorescent proteins are bright, photobleach minimally, express well in the desired cells, do not oligomerize, and generate or incorporate exogenous fluorophores efficiently. Coral-derived red fluorescent proteins require oxygen for fluorophore formation and release two hydrogen peroxide molecules. New fluorescent proteins based on phytochrome and phycobiliproteins use biliverdin IXα as fluorophores, do not require oxygen for maturation to image anaerobic organisms and tumor core, and do not generate hydrogen peroxide. The small Ultra-Red Fluorescent Protein (smURFP) was evolved from a cyanobacterial phycobiliprotein to covalently attach biliverdin as an exogenous fluorophore. The small Ultra-Red Fluorescent Protein is biophysically as bright as the enhanced green fluorescent protein, is exceptionally photostable, used for biosensor development, and visible in living mice. Novel applications of smURFP include in vitro protein diagnostics with attomolar (10−18 M) sensitivity, encapsulation in viral particles, and fluorescent protein nanoparticles. However, the availability of biliverdin limits the fluorescence of biliverdin-attaching fluorescent proteins; hence, extra biliverdin is needed to enhance brightness. New methods for improved biliverdin bioavailability are necessary to develop improved bright far-red and near-infrared fluorescent proteins for noninvasive imaging in vivo.

Protective effect of chitooligosaccharides on hydrogen peroxide-induced PC-12 cells death by inhibition of oxidative damage

2010 ◽  
Vol 34 (8) ◽  
pp. S27-S27
Author(s):  
Xueling Dai ◽  
Ping Chang ◽  
Ke Xu ◽  
Changjun Lin ◽  
Hanchang Huang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Damage ◽  
Protective Effect ◽  
Pc 12 Cells ◽  
Cells Death

Signal-regulated oxidation of proteins via MICAL

2020 ◽  
Vol 48 (2) ◽  
pp. 613-620
Author(s):  
Clara Ortegón Salas ◽  
Katharina Schneider ◽  
Christopher Horst Lillig ◽  
Manuela Gellert
Keyword(s):  
Signal Transduction ◽  
Hydrogen Peroxide ◽  
Cell Death ◽  
Redox Regulation ◽  
Signal Transduction Pathways ◽  
Cellular Functions ◽  
Intracellular Signals ◽  
Amino Acid Side Chains ◽  
Specific Receptors ◽  
Sulfur Containing

Processing of and responding to various signals is an essential cellular function that influences survival, homeostasis, development, and cell death. Extra- or intracellular signals are perceived via specific receptors and transduced in a particular signalling pathway that results in a precise response. Reversible post-translational redox modifications of cysteinyl and methionyl residues have been characterised in countless signal transduction pathways. Due to the low reactivity of most sulfur-containing amino acid side chains with hydrogen peroxide, for instance, and also to ensure specificity, redox signalling requires catalysis, just like phosphorylation signalling requires kinases and phosphatases. While reducing enzymes of both cysteinyl- and methionyl-derivates have been characterised in great detail before, the discovery and characterisation of MICAL proteins evinced the first examples of specific oxidases in signal transduction. This article provides an overview of the functions of MICAL proteins in the redox regulation of cellular functions.

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