1-Methyl-4-aryl-urazole (MAUra) labels tyrosine in proximity to ruthenium photocatalysts

2018 ◽  
Vol 54 (46) ◽  
pp. 5871-5874 ◽  
Author(s):  
Shinichi Sato ◽  
Kensuke Hatano ◽  
Michihiko Tsushima ◽  
Hiroyuki Nakamura
Keyword(s):  
Tyrosyl Radical ◽  
Tyrosine Residues ◽  
Radical Trapping ◽  
Trapping Agent

The 1-methyl-4-aryl-urazole (MAUra) structure was found to be a novel tyrosyl radical trapping agent to label tyrosine residues effectively in proximity to ruthenium photocatalysts.

Visible-Light Photosensitized Aryl and Alkyl Decarboxylative Carbon-Heteroatom and Carbon-Carbon Bond Formations

2019 ◽  
Author(s):  
Tuhin Patra ◽  
Satobhisha Mukherjee ◽  
Jiajia Ma ◽  
Felix Strieth-Kalthoff ◽  
Frank Glorius
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Alkyl Radical ◽  
General Strategy ◽  
Alkyl Radicals ◽  
Bond Forming ◽  
Radical Trapping ◽  
Carbon Carbon Bond ◽  
Radical Generation ◽  
Trapping Agent

<sub>A general strategy to access both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters has been developed. An energy transfer mediated homolysis of unsymmetrical sigma-bonds for a concerted fragmentation/decarboxylation process is involved. As a result, an independent aryl/alkyl radical generation step enables a series of key C-X and C-C bond forming reactions by simply changing the radical trapping agent.</sub>

Identification of protein-derived tyrosyl radical in the reaction of cytochrome c and hydrogen peroxide: characterization by ESR spin-trapping, HPLC and MS

2002 ◽  
Vol 363 (2) ◽  
pp. 281-288 ◽  
Author(s):  
Steven Yue QIAN ◽  
Yeong-Renn CHEN ◽  
Leesa J. DETERDING ◽  
Yang C. FANN ◽  
Colin F. CHIGNELL ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Uv Irradiation ◽  
Phenyl Ring ◽  
Esr Spectra ◽  
Trapping Site ◽  
Spectrometric Analysis ◽  
Tyrosyl Radical ◽  
Radical Trapping ◽  
Radical Adduct ◽  
Hplc Peak

The reaction of cytochrome c and H2O2 is known to form a protein-centred radical that can be detected with the spin trap 2-methyl-2-nitrosopropane (MNP). To characterize the MNP/tyrosyl adduct structure that had previously been determined incorrectly [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498–15503], we eliminated unreasonable structure models by ESR studies with a series of 13C-labelled tyrosines, and photochemically synthesized an authentic MNP/tyrosyl adduct that has its trapping site on the C-3 position of the tyrosine phenyl ring. The observation of the identical ESR spectra for this radical adduct from the UV irradiation of 3-iodo-tyrosine and the adduct from the cytochrome c reaction demonstrated that the radical trapping site of MNP/tyrosyl is located on the equivalent C-3/C-5 positions instead of the C-1 position, as was proposed by Barr et al. In an on-line HPLC/ESR system, an identical retention time (17.7min) was observed for the ESR-active HPLC peak of the MNP/tyrosyl adduct from the following three reactions: (i) the tyrosine oxidation via horseradish peroxidase/H2O2; (ii) UV irradiation of 3-iodo-tyrosine and (iii) the reaction of cytochrome c with H2O2. This result demonstrated that the radical adducts of all three reactions are most probably the same. The mass spectrometric analysis of the HPLC fractions from reactions (i) and (ii) showed an ion at m/z 267 attributed to the MNP/tyrosyl adduct. We conclude that the cytochrome c-derived tyrosyl radical was trapped by MNP, leading to a persistent radical adduct at the C-3/C-5 positions of the tyrosine phenyl ring.

Photooxidation of cobalt(II) meso-tetraphenylporphyrin by p-benzoquinone and its mechanism studied by optical absorption and resonance Raman spectroscopies

2003 ◽  
Vol 07 (08) ◽  
pp. 540-547
Author(s):  
H. Hming Thanga ◽  
Anandi L. Verma
Keyword(s):  
Cation Radical ◽  
Peroxy Radical ◽  
Metal Center ◽  
Porphyrin Ring ◽  
Experimental Conditions ◽  
Radical Trapping ◽  
Oxygen Oxidation ◽  
Trapping Agent ◽  
Complex Oxidation ◽  
Soret Absorption

Laser excitation of Co II TPP within the Soret absorption band in the presence of p-benzoquinone (p-BQ) results in oxidation of the complex. Oxidation occurs both at the metal center and the porphyrin ring depending upon the experimental conditions. Under anaerobic conditions, oxidation takes place at the metal center to produce the cobaltic species Co III( TPP )+, while in the presence of molecular oxygen oxidation also occurs at the porphyrin ring giving Co III( TPP )2+• cation radical as oxidation product. From the inhibiting effect of peroxy radical trapping agent on the photooxidation of Co II TPP under aerobic conditions, the two-electron oxidation is suggested to involve solvent radicals and we discuss the mechanistic details of the process in this work.

scholarly journals New Method in Free Radical Chemistry Using 2,4-Diphenyl-4-methyl-1-pentene as Radical Trapping Agent

1997 ◽  
Vol 29 (4) ◽  
pp. 366-369 ◽  
Author(s):  
Yasumasa Watanabe ◽  
Hideyo Ishigaki ◽  
Hiroshi Okada ◽  
Shuji Suyama
Keyword(s):  
Free Radical ◽  
New Method ◽  
Radical Chemistry ◽  
Radical Trapping ◽  
Free Radical Chemistry ◽  
Trapping Agent

Peroxynitrite-dependent modifications of tyrosine residues in hemoglobin. Formation of tyrosyl radical(s) and 3-nitrotyrosine

Amino Acids ◽  
2003 ◽  
Vol 25 (3-4) ◽  
pp. 341-350 ◽  
Author(s):  
D. Pietraforte ◽  
A. M. Salzano ◽  
G. Marino ◽  
M. Minetti
Keyword(s):  
Tyrosyl Radical ◽  
Tyrosine Residues

3-Nitrotyrosine and related derivatives in proteins: precursors, radical intermediates and impact in function

2020 ◽  
Vol 64 (1) ◽  
pp. 111-133 ◽  
Author(s):  
Nicolás Campolo ◽  
Federico M. Issoglio ◽  
Darío A. Estrin ◽  
Silvina Bartesaghi ◽  
Rafael Radi
Keyword(s):  
Reactive Species ◽  
Side Chain ◽  
Tyrosyl Radical ◽  
Post Translational Modification ◽  
Tyrosine Residues ◽  
Oxidative Products ◽  
Usual Process ◽  
And Function

Abstract Oxidative post-translational modification of proteins by molecular oxygen (O2)- and nitric oxide (•NO)-derived reactive species is a usual process that occurs in mammalian tissues under both physiological and pathological conditions and can exert either regulatory or cytotoxic effects. Although the side chain of several amino acids is prone to experience oxidative modifications, tyrosine residues are one of the preferred targets of one-electron oxidants, given the ability of their phenolic side chain to undergo reversible one-electron oxidation to the relatively stable tyrosyl radical. Naturally occurring as reversible catalytic intermediates at the active site of a variety of enzymes, tyrosyl radicals can also lead to the formation of several stable oxidative products through radical–radical reactions, as is the case of 3-nitrotyrosine (NO2Tyr). The formation of NO2Tyr mainly occurs through the fast reaction between the tyrosyl radical and nitrogen dioxide (•NO2). One of the key endogenous nitrating agents is peroxynitrite (ONOO−), the product of the reaction of superoxide radical (O2•−) with •NO, but ONOO−-independent mechanisms of nitration have been also disclosed. This chemical modification notably affects the physicochemical properties of tyrosine residues and because of this, it can have a remarkable impact on protein structure and function, both in vitro and in vivo. Although low amounts of NO2Tyr are detected under basal conditions, significantly increased levels are found at pathological states related with an overproduction of reactive species, such as cardiovascular and neurodegenerative diseases, inflammation and aging. While NO2Tyr is a well-established stable oxidative stress biomarker and a good predictor of disease progression, its role as a pathogenic mediator has been laboriously defined for just a small number of nitrated proteins and awaits further studies.

Visible-Light Photosensitized Aryl and Alkyl Decarboxylative Carbon-Heteroatom and Carbon-Carbon Bond Formations

2019 ◽  
Author(s):  
Frank Glorius ◽  
Tuhin Patra ◽  
Satobhisha Mukherjee ◽  
Jiajia Ma ◽  
Felix Strieth-Kalthoff
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Alkyl Radical ◽  
General Strategy ◽  
Alkyl Radicals ◽  
Bond Forming ◽  
Radical Trapping ◽  
Carbon Carbon Bond ◽  
Radical Generation ◽  
Trapping Agent

<sub>A general strategy to access both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters has been developed. An energy transfer mediated homolysis of unsymmetrical sigma-bonds for a concerted fragmentation/decarboxylation process is involved. As a result, an independent aryl/alkyl radical generation step enables a series of key C-X and C-C bond forming reactions by simply changing the radical trapping agent.</sub>

Pharmacokinetics of NXY-059, a nitrone-based free radical trapping agent, in healthy young and elderly subjects

2002 ◽  
Vol 11 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Charlotte Edenius ◽  
Stig Strid ◽  
Olof Borgå ◽  
Anna Breitholtz-Emanuelsson ◽  
Kerstin Lanbeck Vallén ◽  
...  
Keyword(s):  
Free Radical ◽  
Elderly Subjects ◽  
Radical Trapping ◽  
Young And Elderly Subjects ◽  
Trapping Agent
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