Effect of amino acids on X-ray-induced hydrogen peroxide and hydroxyl radical formation in water and 8-oxoguanine in DNA

Abstract

Generation of hydrogen peroxide and hydroxyl radicals in L-amino acid solutions in phosphate buffer, pH 7.4, under X-ray irradiation was determined by enhanced chemiluminescence in the luminol-p-iodophenol-peroxidase system and using the fluorescent probe coumarin-3-carboxylic acid, respectively. Amino acids are divided into three groups according to their effect on the hydrogen peroxide formation under irradiation: those decreasing yield of H2O2, having no effect, and increasing its yield. All studied amino acids at 1 mM concentration decrease the yield of hydroxyl radicals in solution under X-ray irradiation. However, the highest effect is observed in the order: Cys > His > Phe = Met = Trp > Tyr. At Cys, Tyr, and His concentrations close to physiological, the yield of hydroxyl radicals decreases significantly. Immunoenzyme analysis using monoclonal antibodies to 8-oxoguanine (8-oxo-7,8-dihydroguanine) was applied to study the effect of amino acids with the most pronounced antioxidant properties (Cys, Met, Tyr, Trp, Phe, His, Lys, Arg, Pro) on 8-oxoguanine formation in vitro under X-ray irradiation. It is shown that amino acids decrease the content of 8-oxoguanine in DNA. These amino acids within DNA-binding proteins may protect intracellular DNA against oxidative damage caused by formation of reactive oxygen species in conditions of moderate oxidative stress.

Prevention and Mitigation of Acute Death of Mice after Abdominal Irradiation by the Antioxidant N-Acetyl-cysteine (NAC)

“…In addition to its well-known role as the rate-limiting precursor of the natural free radical scavenger glutathione (39), NAC has also been found to possess catalase and glutathione reductase activities (40). Furthermore, cysteine has been shown to inhibit X-ray-induced hydroxyl radical generation in cell-free l -amino acid solutions (41). At present, we do not know how much each of these actions of NAC contributes to the beneficial effects observed in our animal model.…”

New Organosilicon Composite Based on Borosiloxane and Zinc Oxide Nanoparticles Inhibits Bacterial Growth, but Does Not Have a Toxic Effect on the Development of Animal Eukaryotic Cells

“…The optical samples density was measured on a plate photometer (Titertek Multiscan, Vantaa, Finland) at λ = 405 nm. The method is described in more detail earlier [33]. Table 3 contains the calibration data used to measure the concentration of 8-oxoGua in DNA.…”

Using of Magnetron Sputtering for Biocompatible Composites Creating

“…Composites Ta-TiNi and Ti-TiNi were also tested for biocompatibility. The effect on the formation of H 2 O 2 in the phosphate buffer (pH 6.8) on heating (37°C) for 200 min in the enhanced chemiluminescence system (luminol-piodophenol-peroxidase) [32] was studied. Sputtering of titanium and tantalum decreases the concentration of hydrogen peroxide formed by approximately 40 (6.5 ± 0.5 nM) and 60% (4.5 ± 0.3 nM), respectively, both close to the media concentration 3.2 ± 0.2 nM.…”