scholarly journals Reversible redox reactions in metal-supported porphyrin: the role of spin and oxidation state

Author(s):  
Iulia Cojocariu ◽  
Silvia Carlotto ◽  
Giovanni Zamborlini ◽  
Matteo Jugovac ◽  
Luca Schio ◽  
...  

The reduced Co(i) metal ion in the molecular array facilitates the formation of the cobalt–ligand chemical bond already at RT. We demonstrate that molecular reactivity goes beyond the sole presence of unpaired electrons in the valence shell.

2018 ◽  
Vol 1 (2) ◽  
pp. 59-63
Author(s):  
V Kovalenko ◽  
A Borysova ◽  
I Pliuta ◽  
R Likhnovsky

This article analyzes the regulatory documents on determination of protective action time of gas filters and FILTERS-ADSORBER, which are designed for individual and collective protection. The current absence of a current regulatory document in Ukraine is indicated according to which protective action time of filters is determined, adds relevance in the implementation of the method of determining this filter characteristic. The theoretical aspects of effect of absorbing capacity of filters are highlighted, the fundamental principles of adsorption are linked with the time of protective action time of filters against hazardous chemicals. The process of adsorption on the surface and formation of sorption layers in case of polymolecular adsorption is schematically shown, as described by the BET theory. It is indicated that protective action time on the direct depends on particular case of adsorption - chemisorption. The types of adsorption isotherms are considered, they are characterized and the Langmuir and BET equations are given. The protective action of filter as a phenomena of chemisorption on the surface of sorbent is described by the Langmuir isotherm, in particular, parts I and II. When determining protective action time the monomolecular adsorption of hazardous chemical substance occurs with formation of a chemical bond with the surface. The chemical bond is formed from the impregnated catalyst due to the redistribution of electrons. Solutions of metal salts are used as a catalyst, and the metal ion itself acts as an active center during the process of chemisorption. The role of adsorption kinetics in the implementation of sanitary cleaning of gas from the pollutant in the practical plane is considered. The possibility of calculating the amount of a chemical that a sorbent can absorb is shown by constructing an adsorption isotherm of a standard substance and a pollutant adsorption working line. Adsorption isotherm was captured for adsorbent from FG-130 FPK 95 filter on KELVIN 1042 sorptometr.


1975 ◽  
Vol 28 (11) ◽  
pp. 2393 ◽  
Author(s):  
RM Golding ◽  
K Lehtonen ◽  
BJ Ralph

In this study of the fungicidal activity of a series of transition metal ion dithiocarbamates in relation to their electronic structure, a model is presented to interpret the biological activity of these complexes, namely the ability of the complex to fit into a receptor site and its ability to undergo reversible redox reactions at suitable potentials. It is shown that in the case of the iron(III) dithiocarbamate complexes these properties are manifested in the spin state of the iron ion.


2020 ◽  
Vol 16 (3) ◽  
pp. 265-283
Author(s):  
Kyriaki Hatziagapiou ◽  
George I. Lambrou

Background: Reactive oxygen species and reactive nitrogen species, which are collectively called reactive oxygen nitrogen species, are inevitable by-products of cellular metabolic redox reactions, such as oxidative phosphorylation in the mitochondrial respiratory chain, phagocytosis, reactions of biotransformation of exogenous and endogenous substrata in endoplasmic reticulum, eicosanoid synthesis, and redox reactions in the presence of metal with variable valence. Among medicinal plants there is a growing interest in Crocus sativus L. It is a perennial, stemless herb, belonging to Iridaceae family, cultivated in various countries such as Greece, Italy, Spain, Israel, Morocco, Turkey, Iran, India, China, Egypt and Mexico. Objective: The present study aims to address the anti-toxicant role of Crocus sativus L. in the cases of toxin and drug toxification. Materials and Methods: An electronic literature search was conducted by the two authors from 1993 to August 2017. Original articles and systematic reviews (with or without meta-analysis), as well as case reports were selected. Titles and abstracts of papers were screened by a third reviewer to determine whether they met the eligibility criteria, and full texts of the selected articles were retrieved. Results: The authors focused on literature concerning the role of Crocus Sativus L. as an anti-toxicant agent. Literature review showed that Saffron is a potent anti-toxicant agent with a plethora of applications ranging from anti-oxidant properties, to chemotherapy protective effects. Conclusion: Literature findings represented in current review herald promising results for using Crocus Sativus L. and/or its active constituents as anti-toxicant, chemotherapy-induced protection and toxin protection.


2021 ◽  
Vol 22 (4) ◽  
pp. 1991
Author(s):  
Jimok Yoon ◽  
Heng Wu ◽  
Ruei-Jiun Hung ◽  
Jonathan R. Terman

To change their behaviors, cells require actin proteins to assemble together into long polymers/filaments—and so a critical goal is to understand the factors that control this actin filament (F-actin) assembly and stability. We have identified a family of unusual actin regulators, the MICALs, which are flavoprotein monooxygenase/hydroxylase enzymes that associate with flavin adenine dinucleotide (FAD) and use the co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH) in Redox reactions. F-actin is a specific substrate for these MICAL Redox enzymes, which oxidize specific amino acids within actin to destabilize actin filaments. Furthermore, this MICAL-catalyzed reaction is reversed by another family of Redox enzymes (SelR/MsrB enzymes)—thereby revealing a reversible Redox signaling process and biochemical mechanism regulating actin dynamics. Interestingly, in addition to the MICALs’ Redox enzymatic portion through which MICALs covalently modify and affect actin, MICALs have multiple other domains. Less is known about the roles of these other MICAL domains. Here we provide approaches for obtaining high levels of recombinant protein for the Redox only portion of Mical and demonstrate its catalytic and F-actin disassembly activity. These results provide a ground state for future work aimed at defining the role of the other domains of Mical — including characterizing their effects on Mical’s Redox enzymatic and F-actin disassembly activity.


Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4267
Author(s):  
Kuo-Hui Wu ◽  
Ryota Sakamoto ◽  
Hiroaki Maeda ◽  
Eunice Jia Han Phua ◽  
Hiroshi Nishihara

We developed an efficient and convenient electrochemical method to synthesize π-conjugated redox metal-complex linear polymer wires composed of azobenzene-bridged bis(terpyridine)metal (2-M, M = Fe, Ru) units covalently immobilized on glassy carbon (GC). Polymerization proceeds by electrochemical oxidation of bis(4′-(4-anilino)-2,2′:6′,2″-terpyridine)metal (1-M) in a water–acetonitrile–HClO4 solution, affording ultralong wires up to 7400 mers (corresponding to ca. 15 μm). Both 2-Fe and 2-Ru undergo reversible redox reactions, and their redox behaviors indicate remarkably fast redox conduction. Anisotropic hetero-metal-complex polymer wires with Fe and Ru centers are constructed via stepwise electropolymerization. The cyclic voltammograms of two hetero-metal-complex polymer wires, GC/[2-Fe]–[2-Ru] (3) and GC/[2-Ru]–[2-Fe] (4), show irreversible redox reactions with opposite electron transfer characteristics, indicating redox diodelike behavior. In short, the present electrochemical method is useful to synthesize polymer wire arrays and to integrate functional molecules on carbon.


2021 ◽  
Vol 170 ◽  
pp. 800-810
Author(s):  
Yimin Deng ◽  
Raf Dewil ◽  
Lise Appels ◽  
Shuo Li ◽  
Jan Baeyens ◽  
...  

Author(s):  
Stephanie Probst ◽  
Johannes Fels ◽  
Bettina Scharner ◽  
Natascha A. Wolff ◽  
Eleni Roussa ◽  
...  

AbstractThe liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe2+ overload. The nephrotoxic non-essential metal ion Cd2+ can displace Fe2+ from cellular biomolecules, causing oxidative stress and cell death. The role of hepcidin in Fe2+ and Cd2+ toxicity was assessed in mouse renal cortical [mCCD(cl.1)] and inner medullary [mIMCD3] collecting duct cell lines. Cells were exposed to equipotent Cd2+ (0.5–5 μmol/l) and/or Fe2+ (50–100 μmol/l) for 4–24 h. Hepcidin (Hamp1) was transiently silenced by RNAi or overexpressed by plasmid transfection. Hepcidin or catalase expression were evaluated by RT-PCR, qPCR, immunoblotting or immunofluorescence microscopy, and cell fate by MTT, apoptosis and necrosis assays. Reactive oxygen species (ROS) were detected using CellROX™ Green and catalase activity by fluorometry. Hepcidin upregulation protected against Fe2+-induced mIMCD3 cell death by increasing catalase activity and reducing ROS, but exacerbated Cd2+-induced catalase dysfunction, increasing ROS and cell death. Opposite effects were observed with Hamp1 siRNA. Similar to Hamp1 silencing, increased intracellular Fe2+ prevented Cd2+ damage, ROS formation and catalase disruption whereas chelation of intracellular Fe2+ with desferrioxamine augmented Cd2+ damage, corresponding to hepcidin upregulation. Comparable effects were observed in mCCD(cl.1) cells, indicating equivalent functions of renal hepcidin in different collecting duct segments. In conclusion, hepcidin likely binds Fe2+, but not Cd2+. Because Fe2+ and Cd2+ compete for functional binding sites in proteins, hepcidin affects their free metal ion pools and differentially impacts downstream processes and cell fate.


2008 ◽  
Vol 47 (36) ◽  
pp. 6881-6884 ◽  
Author(s):  
Chris Ritchie ◽  
Carsten Streb ◽  
Johannes Thiel ◽  
Scott G. Mitchell ◽  
Haralampos N. Miras ◽  
...  

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