Hydrogen peroxide

About: Hydrogen peroxide is a research topic. Over the lifetime, 42583 publications have been published within this topic receiving 1043732 citations. The topic is also known as: H2O2 & dioxidane.

Overexpression of peptide-methionine sulfoxide reductase in Saccharomyces cerevisiae and human T cells provides them with high resistance to oxidative stress

Abstract: The yeast peptide-methionine sulfoxide reductase (MsrA) was overexpressed in a Saccharomyces cerevisiae null mutant of msrA by using a high-copy plasmid harboring the msrA gene and its promoter. The resulting strain had about 25-fold higher MsrA activity than its parent strain. When exposed to either hydrogen peroxide, paraquat, or 2,2′-azobis-(2-amidinopropane) dihydrochloride treatment, the MsrA overexpressed strain grew better, had lower free and protein-bound methionine sulfoxide and had a better survival rate under these conditions than did the msrA mutant and its parent strain. Substitution of methionine with methionine sulfoxide in a medium lacking hydrogen peroxide had little effect on the growth pattern, which suggests that the oxidation of free methionine in the growth medium was not the main cause of growth inhibition of the msrA mutant. Ultraviolet A radiation did not result in obvious differences in survival rates among the three strains. An enhanced resistance to hydrogen peroxide treatment was shown in human T lymphocyte cells (Molt-4) that were stably transfected with the bovine msrA and exposed to hydrogen peroxide. The survival rate of the transfected strain was much better than its parent strain when grown in the presence of hydrogen peroxide. These results support the proposition that the msrA gene is involved in the resistance of yeast and mammalian cells to oxidative stress.

Hydrogen peroxide electrochemistry on platinum: towards understanding the oxygen reduction reaction mechanism

Abstract: Understanding the hydrogen peroxide electrochemistry on platinum can provide information about the oxygen reduction reaction mechanism, whether H2O2 participates as an intermediate or not. The H2O2 oxidation and reduction reaction on polycrystalline platinum is a diffusion-limited reaction in 0.1 M HClO4. The applied potential determines the Pt surface state, which is then decisive for the direction of the reaction: when H2O2 interacts with reduced surface sites it decomposes producing adsorbed OH species; when it interacts with oxidized Pt sites then H2O2 is oxidized to O2 by reducing the surface. Electronic structure calculations indicate that the activation energies of both processes are low at room temperature. The H2O2 reduction and oxidation reactions can therefore be utilized for monitoring the potential-dependent oxidation of the platinum surface. In particular, the potential at which the hydrogen peroxide reduction and oxidation reactions are equally likely to occur reflects the intrinsic affinity of the platinum surface for oxygenated species. This potential can be experimentally determined as the crossing-point of linear potential sweeps in the positive direction for different rotation rates, hereby defined as the “ORR-corrected mixed potential” (c-MP).

Degradation of herbicide 4-chlorophenoxyacetic acid by advanced electrochemical oxidation methods.

Abstract: The herbicide 4-chlorophenoxyacetic acid (4-CPA) has been degraded in aqueous medium by advanced electrochemical oxidation processes such as electro-Fenton and photoelectro-Fenton with UV light, using an undivided cell containing a Pt anode In these environmentally clean methods, the main oxidant is the hydroxyl radical produced from Fenton's reaction between Fe2+ added to the medium and H2O2 electrogenerated from an O2-diffusion cathode Solutions of a 4-CPA concentration <400 ppm within the pH range of 20−60 at 35 °C can be completely mineralized at low current by photoelectro-Fenton, while electro-Fenton leads to ca 80% of mineralization 4-CPA is much more slowly degraded by anodic oxidation in the absence and presence of electrogenerated H2O2 4-Chlorophenol, 4-chlorocatechol, and hydroquinone are identified as aromatic intermediates by CG−MS and quantified by reverse-phase chromatography Further oxidation of these chloroderivatives yields stable chloride ions Generated carboxylic acids such as