Protein Oxidation and DNA–Protein Crosslink Induced by Sulfur Dioxide in Lungs, Livers, and Hearts from Mice

Abstract

In this article, protein oxidative damage and DNA–protein crosslinks (DPC) induced by sulfur dioxide (SO₂) in lungs, livers, and hearts of mice were studied. The protein carbonyl (PCO) content was measured using spectrophotometric DNPH assay to reflect the degree of protein oxidative damage, and the DPC coefficient was measured by using a KCl–sodium dodecyl sulfate (SDS) assay to show the degree of DNA damage in lungs, livers, and hearts from mice exposed to SO₂ at various concentrations (0, 14, 28, and 56 mg-m^{− 3}) for 6 h per day for 7 days. The results indicate that SO₂ caused an increase of PCO and DPC level in all organs tested from mice in a concentration-dependent manner. The concentration-response relationships in all organs tested of both female and male mice could be fitted well with monolinear regression equations. The adjusted coefficient R squared of all equations is more than 0.9. These results lead to a conclusion that SO₂ may cause an increase of protein oxidation damage and DNA–protein crosslinking in lungs, livers, and hearts from mice. The rank order of absolute increase in PCO contents and DPC coefficient in three organs from mice compared with controls was lung > liver > heart. Our results also indicated the regulation of PCO and that of DPC induced by SO₂ were conformed to each other; this implies that the protein oxidative damage may be associated with the emergence of DPC.