scholarly journals Redox activity of a dissymmetric ligand bridging divalent ytter-bium and reactive nickel fragments

2021 ◽  
Author(s):  
Ding Wang ◽  
Maxime Tricoire ◽  
Valeriu Cemortan ◽  
Jules Moutet ◽  
Grégory Nocton
Keyword(s):  
Nickel Complex ◽  
Bond Formation ◽  
Lanthanide Complex ◽  
Redox Activity ◽  
Trimeric Complex ◽  
Redox Active ◽  
Divalent Lanthanide

The reaction of a nickel complex bearing a redox-active dissymmetric ligand (Kbimpm) with a divalent lanthanide complex, Cp*2Yb(OEt2) affords an unprecedented, trimeric complex with C(sp3)–C(sp3) bond formation between two ligands in an exo position.

scholarly journals Synthesis, oligomerization and catalytic studies of a redox-active Ni4-cubane: a detailed mechanistic investigation

RSC Advances ◽  
2021 ◽  
Vol 11 (37) ◽  
pp. 22849-22858
Author(s):  
Saroj Kumar Kushvaha ◽  
Maria Francis ◽  
Jayasree Kumar ◽  
Ekta Nag ◽  
Prathap Ravichandran ◽  
...  
Keyword(s):  
Nickel Complex ◽  
Efficient Catalyst ◽  
Aromatic Heterocycles ◽  
Redox Active ◽  
Mechanistic Investigation

A robust tetrameric nickel complex [Ni4((Oal−)2L-Me)4(s)4] (s = solvent) with cubane-like Ni4O4 core topology identified as the efficient catalyst for the diastereoselective cyclopropanation of aromatic heterocycles.

scholarly journals Bioelectrocatalytic cofactor regeneration coupled to CO2 fixation in a redox‐active hydrogel for stereoselective C‐C bond formation

2021 ◽  
Author(s):  
Leonardo Castañeda-Losada ◽  
David Adam ◽  
Nicole Paczia ◽  
Darren Buesen ◽  
Fabian Steffler ◽  
...  
Keyword(s):  
Co2 Fixation ◽  
Bond Formation ◽  
Cofactor Regeneration ◽  
Redox Active

scholarly journals Bioelectrocatalytic Cofactor Regeneration Coupled to CO 2 Fixation in a Redox‐Active Hydrogel for Stereoselective C−C Bond Formation

2021 ◽  
Author(s):  
Leonardo Castañeda‐Losada ◽  
David Adam ◽  
Nicole Paczia ◽  
Darren Buesen ◽  
Fabian Steffler ◽  
...  
Keyword(s):  
Bond Formation ◽  
Cofactor Regeneration ◽  
Redox Active

scholarly journals The ArcB Sensor Kinase of Escherichia coli Autophosphorylates by an Intramolecular Reaction

2010 ◽  
Vol 192 (6) ◽  
pp. 1735-1739 ◽  
Author(s):  
Gabriela R. Peña-Sandoval ◽  
Dimitris Georgellis
Keyword(s):  
Response Regulator ◽  
Bond Formation ◽  
Sensor Kinase ◽  
Two Component System ◽  
Histidine Kinases ◽  
Intramolecular Reaction ◽  
Redox Active ◽  
Intermolecular Disulfide Bond ◽  
Two Component ◽  
Respiratory Conditions

ABSTRACT The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory conditions of growth. ArcB is a tripartite histidine kinase whose activity is regulated by the oxidation of two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation. Here we show that ArcB autophosphorylates through an intramolecular reaction which diverges from the usually envisaged intermolecular autophosphorylation of homodimeric histidine kinases.

scholarly journals Redox-Active Monolayers Self-Assembled on Gold Electrodes—Effect of Their Structures on Electrochemical Parameters and DNA Sensing Ability

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 607 ◽  
Author(s):  
Kamila Malecka ◽  
Shalini Menon ◽  
Gopal Palla ◽  
Krishnapillai Girish Kumar ◽  
Mathias Daniels ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Redox Activity ◽  
Gold Electrodes ◽  
Complex Structures ◽  
Transfer Coefficients ◽  
Sensing Properties ◽  
Redox Active ◽  
Electrochemical Parameters ◽  
Self Assembled

The background: The monolayers self-assembled on the gold electrode incorporated transition metal complexes can act both as receptor (“host” molecules) immobilization sites, as well as transducer for interface recognitions of “guest” molecules present in the aqueous solutions. Their electrochemical parameters influencing the sensing properties strongly depend on the transition metal complex structures. The objectives: The electrochemical characterization of the symmetric terpyridine–M2+–terpyridine and asymmetric dipyrromethene–M2+–terpyridine complexes modified with ssDNA probe covalently attached to the gold electrodes and exploring their ssDNA sensing ability were the main aims of the research presented. The methods: Two transition metal cations have been selected: Cu2+ and Co2+ for creation of redox-active monolayers. The electron transfer coefficients indicating the reversibility and electron transfer rate constant measuring kinetic of redox reactions have been determined for all SAMs studied using: Cyclic Voltammetry, Osteryoung Square-Wave Voltammetry, and Differential Pulse Voltammetry. All redox-active platforms have been applied for immobilization of ssDNA probe. Next, their sensing properties towards complementary DNA target have been explored electrochemically. The results: All SAMs studied were stable displaying quasi-reversible redox activity. The linear relationships between cathodic and anodic current vs. san rate were obtained for both symmetric and asymmetric SAMs incorporating Co2+ and Cu2+, indicating that oxidized and reduced redox sites are adsorbed on the electrode surface. The ssDNA sensing ability were observed in the fM concentration range. The low responses towards non-complementary ssDNA sequences provided evidences for sensors good selectivity. The conclusions: All redox-active SAMs modified with a ssDNA probe were suitable for sensing of ssDNA target, with very good sensitivity in fM range and very good selectivity. The detection limits obtained for SAMs incorporating Cu2+, both symmetric and asymmetric, were better in comparison to SAMs incorporating Co2+. Thus, selection of the right transition metal cation has stronger influence on ssDNA sensing ability, than complex structures.

scholarly journals Selenium Anticancer Properties and Impact on Cellular Redox Status

Antioxidants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 80 ◽  
Author(s):  
Lolita Kuršvietienė ◽  
Aušra Mongirdienė ◽  
Jurga Bernatonienė ◽  
Jurgita Šulinskienė ◽  
Inga Stanevičienė
Keyword(s):  
Anticancer Activity ◽  
Antioxidant Activities ◽  
Chemotherapeutic Agents ◽  
Redox Activity ◽  
Biological Functions ◽  
Cellular Redox ◽  
Selenium Compounds ◽  
Anticancer Properties ◽  
Redox Active ◽  
The Impact

(1) Background: In this review, we provide information published in recent years on the chemical forms, main biological functions and especially on antioxidant and prooxidant activities of selenium. The main focus is put on the impact of selenoproteins on maintaining cellular redox balance and anticancerogenic function. Moreover, we summarize data on chemotherapeutic application of redox active selenium compounds. (2) Methods: In the first section, main aspects of metabolism and redox activity of selenium compounds is reviewed. The second outlines multiple biological functions, asserted when selenium is incorporated into the structure of selenoproteins. The final section focuses on anticancer activity of selenium and chemotherapeutic application of redox active selenium compounds as well. (3) Results: optimal dietary level of selenium ensures its proper antioxidant and anticancer activity. We pay special attention to antioxidant activities of selenium compounds, especially selenoproteins, and their importance in antioxidant defence. It is worth noting, that data on selenium anticancer properties is still contraversive. Moreover, selenium compounds as chemotherapeutic agents usually are used at supranutritional doses. (4) Conclusions: Selenium play a vital role for many organism systems due to its incorporation into selenoproteins structure. Selenium possesses antioxidant activity at optimal doses, while at supranutritional doses, it displays prooxidant activity. Redox active selenium compounds can be used for cancer treatment; recently special attention is put to selenium containing nanoparticles.

Galectin-13/placental protein 13: redox-active disulfides as switches for regulating structure, function and cellular distribution

Glycobiology ◽  
2019 ◽  
Vol 30 (2) ◽  
pp. 120-129 ◽  
Author(s):  
Tong Yang ◽  
Yuan Yao ◽  
Xing Wang ◽  
Yuying Li ◽  
Yunlong Si ◽  
...  
Keyword(s):  
Disulfide Bond ◽  
Disulfide Bonds ◽  
Bond Formation ◽  
Gel Filtration ◽  
Wild Type ◽  
High Concentration ◽  
Redox Active ◽  
Placental Protein ◽  
The Relationship ◽  
Low Expression

Abstract Galectin-13 (Gal-13) plays numerous roles in regulating the relationship between maternal and fetal tissues. Low expression levels or mutations of the lectin can result in pre-eclampsia. The previous crystal structure and gel filtration data show that Gal-13 dimerizes via formation of two disulfide bonds formed by Cys136 and Cys138. In the present study, we mutated them to serine (C136S, C138S and C136S/C138S), crystalized the variants and solved their crystal structures. All variants crystallized as monomers. In the C136S structure, Cys138 formed a disulfide bond with Cys19, indicating that Cys19 is important for regulation of reversible disulfide bond formation in this lectin. Hemagglutination assays demonstrated that all variants are inactive at inducing erythrocyte agglutination, even though gel filtration profiles indicate that C136S and C138S could still form dimers, suggesting that these dimers do not exhibit the same activity as wild-type (WT) Gal-13. In HeLa cells, the three variants were found to be distributed the same as with WT Gal-13. However, a Gal-13 variant (delT221) truncated at T221 could not be transported into the nucleus, possibly explaining why women having this variant get pre-eclampsia. Considering the normally high concentration of glutathione in cells, WT Gal-13 should exist mostly as a monomer in cytoplasm, consistent with the monomeric variant C136S/C138S, which has a similar ability to interact with HOXA1 as WT Gal-13.

scholarly journals Stepwise synthesis of a Ru4Cd4 coordination cage using inert and labile subcomponents: introduction of redox activity at specific sites

2014 ◽  
Vol 50 (48) ◽  
pp. 6330-6332 ◽  
Author(s):  
Alexander J. Metherell ◽  
Michael D. Ward
Keyword(s):  
Binding Sites ◽  
Redox Activity ◽  
Stepwise Synthesis ◽  
Redox Active

Combination of four [RuL3]2+ units, each with three pendant binding sites, and four Cd2+ ions affords the redox-active, heteronuclear, cubic cage [Ru4Cd4L12]16+.

Photocatalytic redox reactions with metalloporphyrins

2020 ◽  
Vol 24 (01n03) ◽  
pp. 21-32 ◽  
Author(s):  
Shunichi Fukuzumi ◽  
Yong-Min Lee ◽  
Wonwoo Nam
Keyword(s):  
Hydrogen Evolution ◽  
Redox Reactions ◽  
Bond Formation ◽  
Visible Region ◽  
Photosynthetic Reaction Center ◽  
Structure And Function ◽  
Free Base ◽  
Redox Catalyst ◽  
Redox Active ◽  
And Function

Metalloporphyrinoids are utilized as efficient sensitizers and catalysts in photosynthesis and the reverse reaction that is respiration. Because metalloporphyrinoids show strong absorption in the visible region and redox active, metalloporphyrinoids are also suited as photoredox catalysts for photo-driven redox reactions using solar energy. In particular, metalloporphyrins are utilized as pivotal components to mimic the structure and function of the photosynthetic reaction center. Metalloporphyrins are used as photoredox catalysts for hydrogen evolution from electron and proton sources combining hydrogen evolution catalysts. Metalloporphyrins also act as thermal redox catalysts for photocatalytic reduction of CO2 with photoredox catalysts. Metalloporphyrins are also used as dual catalysts for a photoredox catalyst for oxygenation of substrates with H2O and a redox catalyst for O2 reduction when dioxygen is used as a two-electron oxidant and H2O as an oxygen source, both of which are the greenest reactants. Free base porphyrins can also be employed as promising photoredox catalysts for C–C bond formation reactions.

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