Redox proteomics: Methods for the identification and enrichment of redox-modified proteins and their applications

PTMs are defined as covalent additions to functional groups of amino acid residues in proteins like phosphorylation, glycosylation, S-nitrosylation, acetylation, methylation, lipidation, SUMOylation as well as oxidation. Oxidation of proteins has been characterized as a double-edged sword. While oxidative modifications, in particular of cysteine residues, are widely involved in the regulation of cellular homeostasis, oxidative stress resulting in the oxidation of biomolecules along with the disruption of their biological functions can be associated with the development of diseases, such as cancer, diabetes, and neurodegenerative diseases, respectively. This is also the case for advanced glycation end products, which result from chemical reactions of keto compounds such as oxidized sugars with proteins. The role of oxidative modifications under physiological and pathophysiological conditions remains largely unknown. Recently, novel technologies have been established that allow the enrichment, identification, and characterization of specific oxidative PTMs (oxPTMs). This is essential to develop strategies to prevent and treat diseases that are associated with oxidative stress. Therefore this review will focus on (i) the methods and technologies, which are currently applied for the detection, identification, and quantification of oxPTMs including the design of high throughput approaches and (ii) the analyses of oxPTMs related to physiological and pathological conditions.