Distonic radical anion species in cysteine oxidation processes

2020 ◽  
Vol 22 (31) ◽  
pp. 17554-17558
Author(s):  
Zhengbo Qin ◽  
Gao-Lei Hou ◽  
Zheng Yang ◽  
Marat Valiev ◽  
Xue-Bin Wang
Keyword(s):  
Radical Anion ◽  
Cysteine Oxidation ◽  
Homo Energy ◽  
Oxidation Processes ◽  
Oxidation Step ◽  
Anion Species

In contrast to the first reversible oxidation step being associated with sulfinate species, a novel distonic radical anion, •OS–CH2CH(NH2)–COO− has been identified with an inverted SOMO–HOMO energy order that can be restored via protonation.

Photophysical and Electrochemical Properties of New Bacteriochlorins and Characterization of Radical Cation and Radical Anion Species

2002 ◽  
Vol 106 (20) ◽  
pp. 5105-5113 ◽  
Author(s):  
Shunichi Fukuzumi ◽  
Kei Ohkubo ◽  
Yihui Chen ◽  
Ravindra K. Pandey ◽  
Riqiang Zhan ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Radical Cation ◽  
Radical Anion ◽  
Anion Species

scholarly journals Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

2016 ◽  
Vol 12 ◽  
pp. 2450-2456 ◽  
Author(s):  
Nikolay O Chalkov ◽  
Vladimir K Cherkasov ◽  
Gleb A Abakumov ◽  
Andrey G Starikov ◽  
Viacheslav A Kuropatov
Keyword(s):  
Density Distribution ◽  
Spin Density ◽  
Epr Spectroscopy ◽  
Radical Anion ◽  
Copper Cation ◽  
Chemical Oxidation ◽  
Spin Density Distribution ◽  
Coordination Sites ◽  
Redox Forms ◽  
Anion Species

The chemical oxidation and reduction processes of deprotonated, direduced o-quinone-exTTF-o-quinone in protic solvents were studied by EPR spectroscopy. The formation of relatively stable paramagnetic protonated redox forms of the parent triad was very surprising. The character of spin-density distribution in the semiquinone–quinone and semiquinone–catechol redox forms indicates that the p-phenylene-extended tetrathiafulvalene connector provides a quite effective electronic communication channel between dioxolene coordination sites. It was found that the deprotonated, direduced o-quinone-exTTF-o-quinone is capable to reduction of the metal copper in solution. The radical anion species formed in this reaction exists in solution as a solvent-separated ion pair with a copper cation. A character of spin-density distribution in a radical anion species leads to the conclusion that the ligand corresponds to type III of the Robin–Day classification.

scholarly journals Evaluation of advanced oxidation processes for ß-blockers degradation: a review

2021 ◽  
Author(s):  
Krisztina Kovács ◽  
Tünde Tóth ◽  
László Wojnárovits
Keyword(s):  
Rate Constants ◽  
Radical Anion ◽  
Advanced Oxidation Processes ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
Advanced Oxidation ◽  
Sulfate Radical ◽  
Oxidation Processes ◽  
Free Radical Chemistry ◽  
Sulfate Radical Anion

Abstract This study summarizes the results of scientific investigations on the removal of the three most-often used ß-blockers (atenolol, metoprolol and propranolol) by various advanced oxidation processes (AOP). The free radical chemistry, rate constants, degradation mechanism and elimination effectiveness of these compounds are discussed together with the technical details of experiments. In most of AOP the degradation is predominantly initiated by hydroxyl radicals. In sulfate radical anion based oxidation processes (SROP) both hydroxyl radical and sulfate radical anion greatly contributes to the degradation. The rate constants of reactions with these two radicals are in the 109–1010 M−1 s−1 range. The degradation products reflect ipso attack, hydroxylation on the aromatic ring and/or the amino moiety and cleavage of the side chain. Among AOP photocatalysis and SROP are the most effective for degradation of the three ß-blockers. The operating parameters have to be optimized to the most suitable effectiveness.

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

CarR, a MarR-family regulator from Corynebacterium glutamicum, modulated antibiotic and aromatic compound resistance

2019 ◽  
Vol 476 (21) ◽  
pp. 3141-3159 ◽  
Author(s):  
Meiru Si ◽  
Can Chen ◽  
Zengfan Wei ◽  
Zhijin Gong ◽  
GuiZhi Li ◽  
...  
Keyword(s):  
Stress Response ◽  
Ligand Binding ◽  
Corynebacterium Glutamicum ◽  
Conformational Changes ◽  
Cysteine Oxidation ◽  
Transcriptional Regulatory ◽  
Ligand Free ◽  
Redox Sensing

Abstract MarR (multiple antibiotic resistance regulator) proteins are a family of transcriptional regulators that is prevalent in Corynebacterium glutamicum. Understanding the physiological and biochemical function of MarR homologs in C. glutamicum has focused on cysteine oxidation-based redox-sensing and substrate metabolism-involving regulators. In this study, we characterized the stress-related ligand-binding functions of the C. glutamicum MarR-type regulator CarR (C. glutamicum antibiotic-responding regulator). We demonstrate that CarR negatively regulates the expression of the carR (ncgl2886)–uspA (ncgl2887) operon and the adjacent, oppositely oriented gene ncgl2885, encoding the hypothetical deacylase DecE. We also show that CarR directly activates transcription of the ncgl2882–ncgl2884 operon, encoding the peptidoglycan synthesis operon (PSO) located upstream of carR in the opposite orientation. The addition of stress-associated ligands such as penicillin and streptomycin induced carR, uspA, decE, and PSO expression in vivo, as well as attenuated binding of CarR to operator DNA in vitro. Importantly, stress response-induced up-regulation of carR, uspA, and PSO gene expression correlated with cell resistance to β-lactam antibiotics and aromatic compounds. Six highly conserved residues in CarR were found to strongly influence its ligand binding and transcriptional regulatory properties. Collectively, the results indicate that the ligand binding of CarR induces its dissociation from the carR–uspA promoter to derepress carR and uspA transcription. Ligand-free CarR also activates PSO expression, which in turn contributes to C. glutamicum stress resistance. The outcomes indicate that the stress response mechanism of CarR in C. glutamicum occurs via ligand-induced conformational changes to the protein, not via cysteine oxidation-based thiol modifications.

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