Identification and characterization of protein cross-links induced by oxidative reactions

Abstract

Protein cross-links are common in biological systems and are generated both deliberately as a part of normal metabolism and also accidently as a result of exposure to external factors such as oxidation and glycation stresses. These cross-links can be both positive and negative for biological function, with high levels of inappropriate cross-links being associated with multiple human pathologies, as well as loss of protein structure and function in the food, agricultural, and pharmaceutical fields. Areas covered: This review covers recent advances in the detection and identification of protein cross-links arising from oxidation reactions, mediated by both radicals and two-electron oxidants. Information on both enzymatic and nonenzymatic cross-linking is reviewed, both where this is intentional, as part of normal metabolism, and accidental and a potential cause of disease. Expert commentary: The advantages and drawbacks of various methods available for the detection, identification, and quantification of these species are discussed, as well as some of the mechanisms and processes known to give rise to these species.

Formation and characterization of crosslinks, including Tyr–Trp species, on one electron oxidation of free Tyr and Trp residues by carbonate radical anion

“…This tenet is supported by the detection of both intra-and intermolecular Tyr-Trp bonds in a number of systems. 36,37,[48][49][50]57 In spite of this, little effort has been expended on understanding the factors that control the formation, accumulation and biological consequences of the generation of this type of species. This is probably, at least in part, due to the absence of robust methods to detect and quantify these adducts.…”

UV oxidation of cyclic AMP receptor protein, a global bacterial gene regulator, decreases DNA binding and cleaves DNA at specific sites

“…The UV-induced CRP cross-links ( Fig. 1D) were characterized using MS with H 2 18 O labelling (reviewed 18 ). This method provided strong evidence for a di-Tyr cross-link between Tyr63 and Tyr41 in a cross-linked peptide (KEMILSYLNQGDFIGELGLFEEGQER) (KAETLYYIVK); this species was not detected in controls.…”

“…Mass spectrometric analysis of cross-linked peptides. Analysis of cross-linked peptides by MS was performed as described previously 18,32 . Briefly, after tryptic peptides were digested in H 2 18 O-or H 2 16 O, they were subjected to solid-phase extraction on activated StageTip C18 reversed-phase discs, and peptides were then dried down (Speedvac concentrator, 3 mins), re-suspended in 10 μl H 2 18 O and H 2 16 O water, respectively, and mixed at a 1:1 ratio immediately prior to analysis.…”

Singlet oxygen‐induced protein aggregation: Lysozyme crosslink formation and nLC‐MS/MS characterization

“…Recently, the group of M.J. Davies presented an overview on the strategies on the detection and identification of protein crosslinks generated via oxidation reactions. They discuss a series of mechanisms involving reactions mediated by both radicals and two‐electron oxidants …”