Radical rearrangement and transfer reactions in proteins

Schöneich, Christian

doi:10.1042/ebc20190046

Cited by 5 publications

(4 citation statements)

References 80 publications

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“…310 The fragmentation of Trp •+ also produces 3-methyleneindolenine (3-MEI) that is prone to react with nucleophilic side chains of amino acid residues in proteins, especially Lys, leading to protein functionalization (Figure 10c). 311 Many products of tryptophan oxidation can activate the aryl hydrocarbon receptor (AhR), which in turn upregulates cytochrome P450 gene expression, including CYP1A1, in skin cells as part of the inflammatory response. Additionally, AhR can activate the MAP kinase pathway by signaling through Src, which can then phosphorylate EGFR.…”

Section: Amino Acidsmentioning

confidence: 99%

“…The cleavage of the Cα–Cβ bond of Trp •+ /Trp • leads to the glycyl radical, Gly • , which is a stabilized species due to captodative (push–pull) effects, − but undergoes HAT to produce glycine or adds oxygen yielding a peroxyl radical that can be reduced to give GlyOOH (Figure b) . The fragmentation of Trp •+ also produces 3-methyleneindolenine (3-MEI) that is prone to react with nucleophilic side chains of amino acid residues in proteins, especially Lys, leading to protein functionalization (Figure c) . Many products of tryptophan oxidation can activate the aryl hydrocarbon receptor (AhR), which in turn upregulates cytochrome P450 gene expression, including CYP1A1 , in skin cells as part of the inflammatory response.…”

Section: Key Endogenous Photosensitizers and Their Targetsmentioning

confidence: 99%

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Endogenous Photosensitizers in Human Skin

2023

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Endogenous photosensitizers play a critical role in both beneficial and harmful light-induced transformations in biological systems. Understanding their mode of action is essential for advancing fields such as photomedicine, photoredox catalysis, environmental science, and the development of sun care products. This review offers a comprehensive analysis of endogenous photosensitizers in human skin, investigating the connections between their electronic excitation and the subsequent activation or damage of organic biomolecules. We gather the physicochemical and photochemical properties of key endogenous photosensitizers and examine the relationships between their chemical reactivity, location within the skin, and the primary biochemical events following solar radiation exposure, along with their influence on skin physiology and pathology. An important take-home message of this review is that photosensitization allows visible light and UV-A radiation to have large effects on skin. The analysis presented here unveils potential causes for the continuous increase in global skin cancer cases and emphasizes the limitations of current sun protection approaches.

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Section: Amino Acidsmentioning

confidence: 99%

Section: Key Endogenous Photosensitizers and Their Targetsmentioning

confidence: 99%

Endogenous Photosensitizers in Human Skin

2023

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“…The significance and impact of selective C(sp 3 )–C(sp 3 ) bond constructions have gained widespread appreciation in recent years. − Hydrogen atom transfer (HAT) processes that enable regioselective functionalization of C–H bonds are strategically valuable because they can enable the formation of bonds between two C(sp 3 ) carbons. − In particular, heteroatom-centered radicals (O • , N • ), which often undergo intramolecular 1,5-HAT reactions to generate translocated carbon-centered radicals (Scheme a), have been well established and widely applied in modern organic synthesis. ,,− In comparison with 1,5-HAT processes, net-1,2-HAT reactions are rare, having been observed with a few oxygen-centered radicals (X = O, Scheme a). , These 1,2-HAT processes are generally initiated by transition-metal catalysts, including Ir, Cu, and Ag catalysts, or undergo photocatalytic reactions (Scheme b). − Another proposed net-1,2-HAT is with aminyl radicals. Aminyl radicals are intermediates in the reaction of amino acid systems with hypochlorite. − In such a process, 1,2-HAT reactions to form captodative C-centered radicals have been proposed, as have both intra- and intermolecular pathways . Evidence for carbon-centered radical products in these systems has been presented in spin trapping experiments by EPR.…”

Section: Introductionmentioning

confidence: 99%

Net-1,2-Hydrogen Atom Transfer of Amidyl Radicals: Toward the Synthesis of 1,2-Diamine Derivatives

et al. 2023

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Hydrogen atom transfer (HAT) processes are among the most useful approaches for the selective construction of C(sp3)–C(sp3) bonds. 1,5-HAT with heteroatom-centered radicals (O•, N•) have been well established and are favored relative to other 1,n-HAT processes. In comparison, net 1,2-HAT processes have been observed infrequently. Herein, the first amidyl radicalls are reported that preferentially undergo a net 1,2-HAT over 1,5-HAT. Beginning with single electron transfer from 2-azaallyl anions to N-alkyl N-aryloxy amides, the latter generate amidyl radicals. The amidyl radical undergoes a net-1,2-HAT to generate a C-centered radical that participates in an intermolecular radical–radical coupling with the 2-azaallyl radical to generate 1,2-diamine derivatives. Mechanistic and EPR experiments point to radical intermediates. Density functional theory calculations provide support for a base-assisted, stepwise-1,2-HAT process. It is proposed that the generation of amidyl radicals under basic conditions can be greatly expanded to access α-amino C-centered radicals that will serve as valuable synthetic intermediates.

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“…However, in this article, reflecting the wider interests noted above, we focus on outlining and illustrating the use of radiolysis methods to generate specific, individual free radicals of interest in the context of peroxynitrite biochemistry and follow their reactions with amino acids, proteins, and other biologically relevant targets. The application and versatility of pulse radiolysis to studying biochemical redox processes has been reviewed by several authors [18][19][20][21]. Herein, we aim to provide both some background discussion and specific illustrations, seeking to complement these other reviews with a focus on how radiolysis studies were adapted and utilized for the biochemical characterization of peroxynitrite-derived radicals.…”

Section: Introductionmentioning

confidence: 99%

Radiolysis Studies of Oxidation and Nitration of Tyrosine and Some Other Biological Targets by Peroxynitrite-Derived Radicals

Folkes

Bartesaghi

Trujillo

et al. 2022

IJMS

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The widespread interest in free radicals in biology extends far beyond the effects of ionizing radiation, with recent attention largely focusing on reactions of free radicals derived from peroxynitrite (i.e., hydroxyl, nitrogen dioxide, and carbonate radicals). These radicals can easily be generated individually by reactions of radiolytically-produced radicals in aqueous solutions and their reactions can be monitored either in real time or by analysis of products. This review first describes the general principles of selective radical generation by radiolysis, the yields of individual species, the advantages and limitations of either pulsed or continuous radiolysis, and the quantitation of oxidizing power of radicals by electrode potentials. Some key reactions of peroxynitrite-derived radicals with potential biological targets are then discussed, including the characterization of reactions of tyrosine with a model alkoxyl radical, reactions of tyrosyl radicals with nitric oxide, and routes to nitrotyrosine formation. This is followed by a brief outline of studies involving the reactions of peroxynitrite-derived radicals with lipoic acid/dihydrolipoic acid, hydrogen sulphide, and the metal chelator desferrioxamine. For biological diagnostic probes such as ‘spin traps’ to be used with confidence, their reactivities with radical species have to be characterized, and the application of radiolysis methods in this context is also illustrated.

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Radical rearrangement and transfer reactions in proteins

Cited by 5 publications

References 80 publications

Endogenous Photosensitizers in Human Skin

Endogenous Photosensitizers in Human Skin

Net-1,2-Hydrogen Atom Transfer of Amidyl Radicals: Toward the Synthesis of 1,2-Diamine Derivatives

Radiolysis Studies of Oxidation and Nitration of Tyrosine and Some Other Biological Targets by Peroxynitrite-Derived Radicals

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