Free radical oxidation of proteins and its relationship with functional state of organisms.

Most reactive oxygen species (ROS) in living organisms are produced as byproducts of many processes. Being highly active, ROS interact with virtually all cellular components particularly modifying their properties. In this review, detailed analysis of chemical modifications of proteins on their interaction with ROS is given with particular interest in cleavage of polypeptide chains and oxidation of side chains of amino acid residues. Special attention has been paid to identification of products of free radical modification of proteins with a focus on the formation of additional carbonyl groups, which are the most frequently used markers of these processes. Functional consequences of protein modification by ROS depend on the nature of ROS and protein as well as particular conditions of their interaction. The relationship between protein oxidation and functional state of organisms, particularly aging, hyperoxia and hypoxia, and heat shock, as well as with different pathologies has been analyzed. The final part of the article is devoted to possible ways of protecting proteins against oxidation in vivo.