RESUMO
It was demonstrated that low-intensity radiation of helium-neon (He-Ne) laser at 632.8nm, which leads to the transition of oxygen to a singlet state, causes the formation of reactive oxygen species (ROS) - hydrogen peroxide, hydroxyl and superoxide (hydroperoxide) radicals - in aqueous solutions. The oxygen effect - dependence of hydrogen peroxide formation on the concentration of molecular oxygen - was shown, and the participation of singlet oxygen, hydroxyl radicals and superoxide (hydroperoxide) radicals in this process was testified. Laser radiation-induced ROS in solutions of blood serum proteins, bovine serum albumin and bovine gamma-globulin, cause the formation of long-lived reactive protein species (LRPS) with a half-life of about 4h. The generation of LRPS caused by laser irradiation results in prolonged several-hour generation of ROS - hydrogen peroxide, hydroxyl and superoxide radicals. As affected by LRPS, coupled radical reactions lead to conversion of dissolved molecular oxygen to hydrogen peroxide. Irradiation with light sources away from the oxygen absorption band is not attended by formation of ROS and LRPS. A consideration is provided for the possible molecular mechanisms of ROS formation under the influence of He-Ne laser irradiation, the role of proteins in their generation and the biological significance of these processes.
Assuntos
Proteínas Sanguíneas/efeitos da radiação , Lasers de Gás , Espécies Reativas de Oxigênio/metabolismo , Animais , Proteínas Sanguíneas/química , Proteínas Sanguíneas/metabolismo , Bovinos , Peróxido de Hidrogênio/metabolismo , Radical Hidroxila/metabolismo , Medições Luminescentes , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Soroalbumina Bovina/efeitos da radiação , Superóxidos/metabolismo , gama-Globulinas/química , gama-Globulinas/metabolismo , gama-Globulinas/efeitos da radiaçãoRESUMO
Low-intensity ultraviolet irradiation was used to generate free-radical activity in lipid-free human gamma-globulin. The changes were monitored by fluorescence spectroscopy and gel filtration chromatography. The pattern and the effect of thiol compounds, free-radical scavengers and antioxidants point to a free-radical-mediated process. Initial energy uptake was probably in the region of aromatic amino acid residues, followed by complex intramolecular rearrangements. Irradiation led to the formation of molecular species and complexes whose fluorescence characteristics were different from those of native gamma-globulin and indistinguishable from those observed in inflammatory exudates.