| Abstract: | The action of 1 mM solutions of L-amino acids in 5 mM phosphate buffer, pH 7.4, on the production of hydrogen peroxide and hydroxyl radicals under the action of X-rays and heating has been studied. Hydrogen peroxide was estimated by the method of enhanced luminescence in a system luminol-paraiodophenol-peroxidase and hydroxyl radicals were determined by using the fluorescence probe coumarin-3-carboxylic acid. It was shown that amino acids can be divided by their influence on H202 formation into three groups: those that reduce the yield of H202, that do not influence it, and that increase it. A similar action of amino acids was observed upon heating, but the composition of the groups was different. All amino acids lowered the formation of hydroxyl radicals under the action of X-rays, and the most effective among them were Cys > His > Phe = Met = Trp > Tyr. Met, His and Phe lowered the amount of hydroxyl radicals by heating, Ser raised it, whereas Tyr and Pro did not change it. Thus, amino acids differently influence the formation of reactive oxygen species by the action of X-rays and heat, and some of amino acids reveal themselves as effective natural antioxidants. |
