Protein carbonylation and oxidative modification of serum proteins by diesel exhaust

Although the overall biology of oxidative protein modifications is complex and remains ill defined, oxidative protein carbonylation is quite well characterized. Carbonylation is an irreversible, non-enzymatic modification of proteins. Carbonyl groups are introduced into proteins by a variety of oxidative pathways. ROS can react directly with the protein or they can react with molecules such as sugars and lipids, generating products called reactive carbonyl species (RCS), which then react with the protein. Air pollution is an external source of free radicals. They have the ability to promote free radical reactions. For this reason the toxicology of particulate matter emitted from diesel engines is a matter of significant concern. Diesel Exhaust Particles can introduce oxidizing species adsorbed on the particles surface such as transition metals and organic compounds into the lungs leading to adverse health outcomes. Although the exact mechanism is unclear, particles play a role in the production of reactive oxygen species. In this study we have investigated the ability of diesel exhaust to bring about protein carbonylation of serum proteins and produce Thiobarbituric acid reactive substances in Low and High density lipoproteins. The diesel exhaust was able to decarboxylate alpha keto acids, a typical reaction catalysed by pro-oxidants. These results suggest that diesel exhaust but not petrol exhaust can cause oxidative stress