ROS and Oxidative Modification of Cellular Components

Abstract

ROS, the inevitable by-products of aerobic metabolism, when got escaped from antioxidant-mediated detoxification and accumulated in high concentration, may react nonspecifically with almost all important biomolecules and cause irreversible damage to those biomolecules which may cause metabolic dysfunction and inactivation of key cellular functions. In fact, there exist several evidences on environmental stress (both abiotic and biotic)-mediated changes in redox status and corresponding modulation of lipid and protein oxidation. ROS-mediated peroxidation of lipid, particularly the membrane lipid peroxidation (MLPO), which is normally linked with aging, senescence, and stress-induced oxidative damages, is extremely important from its mechanistic point of view as it is a unique example of hydrocarbon-centered ROS production in cell. Oxidative modification of proteins, which basically involves through carbonylation, nitrosylation, disulfide linkage formation, glutathionylation, etc., seriously modifies and influences the protein activity and subsequently causes metabolic dysfunction. Though oxidative modifications of important cellular molecules exhibit deteriorative events, in recent times, several works highlighted important physiological roles of such modifications. The most important of which is membrane lipid peroxidation (MLPO). Mechanistically it involves the generation and propagation of lipid radicals, oxygenation and rearrangement of double bonds in the unsaturated lipids, and in due course their destruction. This process always yields a variety of secondary breakdown products, including alcohol, aldehydes, ketones, alkanes, and ethers, and is long being recognized as one of the prime events involved in oxidative damage and cell death. However, several recent works propose that these secondary products of lipid peroxidation, like reactive lipid species (RLS), can instigate cell signaling associated with the induction of antioxidative defense, apoptosis, membrane repair, etc. In this chapter an effort has been made to provide an update on oxidative damages of important cellular components while addressing their roles in deteriorative oxidative damage and adaptive cell signaling. This chapter makes an effort to examine the biochemical aspects of oxidative damage to lipid, protein, and nucleic acids along with the technologies to detect those changes. An additional effort has also been made to unfold the physiological significance of oxidative damages of lipid and protein in context of the recent roles of secondary oxidized products in cell signaling.