EPR study of reaction products of oxides of nitrogen with some organic compounds

Abstract

The possibility of formation of paramagnetic centers in reactions between oxides of nitrogen and saturated and unsaturated fatty acids and aromatic amino acids was studied by an EPR method. During the reaction between NO₂ and oleic acid at 20°C several paramagnetic centers were found to be formed. Saturated fatty acids do not form paramagnetic centers on reacting with NO₂. NO did not form paramagnetic centers, whether with butyric, palmitic, and stearic acids, or with oleic acid. NO₂ was shown to form paramagnetic centers with a saturated solution of tyrosine. The formation of paramagnetic centers was not observed as a result of the reaction of NO and NO₂ with saturated solutions of phenylalanine and tryptophan. It is postulated that unsaturated fatty acids and tyrosine residues of membrane lipoprotein complexes may act as targets for reaction with NO₂, and that the formation of paramagnetic centers in the reaction between NO₂ and the above-mentioned substances is the primary act of injury to the membranes.