Reactive Oxygen Species
Introduction The increasing concentration of oxygen level in the atmosphere near about 2.5 billion ago, oxygenic photosynthesis by cyanobacteria leads to the evolution of aerobic respiration leading to the development of complex eukaryotic organisms. All the aerobic organisms depends upon the cellular respiration and some of the derivatives of oxygen are highly toxic for the cells. Reactive oxygen species, reactive oxygen intermediates and reactive nitrogen species have been used to define the highly reactive oxygen bearing molecules. Hydroxyl and peroxyl radicals, hydrogen peroxide and superoxide radical anions are some of the species responsible for the damage of the fatty acids, DNA and proteins as well as other cellular components. The redox reaction is typically involved in controlling production of reactive oxygen and nitrogen species. They can, in turn, react with specific functional group of target proteins like clusters, cysteines etc. that lead to covalent protein modificat