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International Journal of Molecular... Jun 2022The synthesis and structural characterization of a series of supramolecular complexes of bicyclic cationic pyridine-fused 1,2,4-selenodiazoles with various anions is...
The synthesis and structural characterization of a series of supramolecular complexes of bicyclic cationic pyridine-fused 1,2,4-selenodiazoles with various anions is reported. The binding of trifluoroacetate, tetrachloroaurate, tetraphenylborate, perrhenate, and pertechnetate anions in the solid state is regarded. All the anions interact with selenodiazolium cations exclusively via a pair of "chelating" Se⋯O and H⋯O non-covalent interactions, which make them an attractive, novel, non-classical supramolecular recognition unit or a synthon. Trifluoroacetate salts were conveniently generated via novel oxidation reaction of 2,2'-dipyridyl diselenide with bis(trifluoroacetoxy)iodo)benzene in the presence of corresponding nitriles. Isolation and structural characterization of transient 2-pyridylselenyl trifluoroacetate was achieved. X-ray analysis has demonstrated that the latter forms dimers in the solid state featuring very short and strong Se⋯O and Se⋯N ChB contacts. 1,2,4-Selenodiazolium trifluoroacetates or halides show good solubility in water. In contrast, (AuCl), (ReO), or (TcO) derivatives immediately precipitate from aqueous solutions. Structural features of these supramolecular complexes in the solid state are discussed. The nature and energies of the non-covalent interactions in novel assembles were studied by the theoretical methods. To the best of our knowledge, this is the first study that regards perrhenate and pertechnetate as acceptors in ChB interactions. The results presented here will be useful for further developments in anion recognition and precipitation involving cationic 1,2,4-selenodiazoles.
Topics: Anions; Cations; Models, Theoretical; Salts; Sodium Pertechnetate Tc 99m; Trifluoroacetic Acid; Water
PubMed: 35742815
DOI: 10.3390/ijms23126372 -
The Journal of Biological Chemistry Jul 2017Na/K-ATPase transports Na and K ions across the cell membrane via an ion-binding site becoming alternatively accessible to the intra- and extracellular milieu by...
Na/K-ATPase transports Na and K ions across the cell membrane via an ion-binding site becoming alternatively accessible to the intra- and extracellular milieu by conformational transitions that confer marked changes in ion-binding stoichiometry and selectivity. To probe the mechanism of these changes, we used molecular simulation and free-energy perturbation approaches to identify probable protonation states of Na- and K-coordinating residues in E1P and E2P conformations of Na/K-ATPase. Analysis of these simulations revealed a molecular mechanism responsible for the change in protonation state: the conformation-dependent binding of an anion (a chloride ion in our simulations) to a previously unrecognized cytoplasmic site in the loop between transmembrane helices 8 and 9, which influences the electrostatic potential of the crucial Na-coordinating residue Asp This mechanistic model is consistent with experimental observations and provides a molecular-level picture of how E1P to E2P enzyme conformational transitions are coupled to changes in ion-binding stoichiometry and selectivity.
Topics: Animals; Anions; Binding Sites; Cytoplasm; Models, Molecular; Molecular Dynamics Simulation; Protein Conformation; Sodium-Potassium-Exchanging ATPase; Swine; Thermodynamics
PubMed: 28588025
DOI: 10.1074/jbc.M117.779090 -
Molecules (Basel, Switzerland) Jun 2020Polyhydroborate salts represent the important class of energy materials attracting significant recent attention. Some of these salts exhibit promising hydrogen storage... (Review)
Review
Polyhydroborate salts represent the important class of energy materials attracting significant recent attention. Some of these salts exhibit promising hydrogen storage properties and/or high ionic conductivities favorable for applications as solid electrolytes in batteries. Two basic types of thermally activated atomic jump motion are known to exist in these materials: the reorientational (rotational) motion of complex anions and the translational diffusion of cations or complex anions. The present paper reviews recent progress in nuclear magnetic resonance (NMR) studies of both reorientational and diffusive jump motion in polyhydroborate salts. The emphasis is put on sodium and lithium -borates exhibiting high ionic conductivity and on borohydride-based systems showing extremely fast reorientational motion down to low temperatures. For these systems, we discuss the effects of order-disorder phase transitions on the parameters of reorientations and diffusive jumps, as well as the mechanism of low-temperature rotational tunneling.
Topics: Anions; Bromates; Cations; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Conformation; Salts
PubMed: 32604750
DOI: 10.3390/molecules25122940 -
Molecules (Basel, Switzerland) Feb 2021Biodegradable and antimicrobial waterborne polyurethane dispersions (PUDs) and their casted solid films have recently emerged as important alternatives to their... (Review)
Review
Biodegradable and antimicrobial waterborne polyurethane dispersions (PUDs) and their casted solid films have recently emerged as important alternatives to their solvent-based and non-biodegradable counterparts for various applications due to their versatility, health, and environmental friendliness. The nanoscale morphology of the PUDs, dispersion stability, and the thermomechanical properties of the solid films obtained from the solvent cast process are strongly dependent on several important parameters, such as the preparation method, polyols, diisocyanates, solid content, chain extension, and temperature. The biodegradability, biocompatibility, antimicrobial properties and biomedical applications can be tailored based on the nature of the polyols, polarity, as well as structure and concentration of the internal surfactants (anionic or cationic). This review article provides an important quantitative experimental basis and structure evolution for the development and synthesis of biodegradable waterborne PUDs and their solid films, with prescribed macromolecular properties and new functions, with the aim of understanding the relationships between polymer structure, properties, and performance. The review article will also summarize the important variables that control the thermomechanical properties and biodegradation kinetics, as well as antimicrobial and biocompatibility behaviors of aqueous PUDs and their films, for certain industrial and biomedical applications.
Topics: Anions; Anti-Infective Agents; Biodegradable Plastics; Humans; Polymers; Polyurethanes; Solvents; Surface-Active Agents; Water
PubMed: 33670378
DOI: 10.3390/molecules26040961 -
Molecules (Basel, Switzerland) Nov 2020Synthetic anion transporters that facilitate chloride transport are promising candidates for channelopathy treatments. However, most anion transporters exhibit an...
Synthetic anion transporters that facilitate chloride transport are promising candidates for channelopathy treatments. However, most anion transporters exhibit an undesired side effect of facilitating proton transport via interacting with fatty acids present in the membrane. To address the limitation, we here report the use of a new tetrapodal scaffold to maximize the selective interaction with spherical chloride over binding the carboxylate headgroup of fatty acids. One of the new transporters demonstrated a high selectivity for chloride uniport over fatty acid-induced proton transport while being >10 times more active in chloride uniport than strapped calixpyrroles that were previously the only class of compounds known to possess similar selectivity properties.
Topics: Anion Transport Proteins; Anions; Chlorides; Chromatography, Thin Layer; Crystallography, X-Ray; Fatty Acids; Ion Transport; Lipid Bilayers; Magnetic Resonance Spectroscopy; Nitrates; Pyrenes; Sulfonic Acids
PubMed: 33172141
DOI: 10.3390/molecules25215179 -
IUBMB Life Apr 2014The review describes molecular and functional properties of the volume regulated anion channel and Ca(2+)-dependent Cl(-) channels belonging to the anoctamin family with... (Review)
Review
The review describes molecular and functional properties of the volume regulated anion channel and Ca(2+)-dependent Cl(-) channels belonging to the anoctamin family with emphasis on physiological importance of these channels in regulation of cell volume, cell migration, cell proliferation, and programmed cell death. Finally, we discuss the role of Cl(-) channels in various diseases.
Topics: Animals; Anions; Calcium; Cell Physiological Phenomena; Chloride Channels; Humans
PubMed: 24771413
DOI: 10.1002/iub.1266 -
Biochemical Society Transactions Dec 2022Chloride is the most abundant inorganic anions in almost all cells and in human circulation systems. Its homeostasis is therefore important for systems physiology and...
Chloride is the most abundant inorganic anions in almost all cells and in human circulation systems. Its homeostasis is therefore important for systems physiology and normal cellular activities. This topic has been extensively studied with chloride loaders and extruders expressed in both cell surfaces and intracellular membranes. With the newly discovered, large-conductance, highly selective Cl- channel formed by membrane-bound chromogranin B (CHGB), which differs from all other known anion channels of conventional transmembrane topology, and is distributed in plasma membranes, endomembrane systems, endosomal, and endolysosomal compartments in cells expressing it, we will discuss the potential physiological importance of the CHGB channels to Cl- homeostasis, cellular excitability and volume control, and cation uptake or release at the cellular and subcellular levels. These considerations and CHGB's association with human diseases make the CHGB channel a possible druggable target for future molecular therapeutics.
Topics: Humans; Chlorides; Chloride Channels; Chromogranin B; Anions; Homeostasis
PubMed: 36511243
DOI: 10.1042/BST20220435 -
The FEBS Journal Nov 2011Plant anion channels allow the efflux of anions from cells. They are involved in turgor pressure control, changes in membrane potential, organic acid excretion,... (Review)
Review
Plant anion channels allow the efflux of anions from cells. They are involved in turgor pressure control, changes in membrane potential, organic acid excretion, tolerance to salinity and inorganic anion nutrition. The recent molecular identification of anion channel genes in guard cells and in roots allows a better understanding of their function and of the mechanisms that control their activation.
Topics: Anions; Ion Channels; Membrane Potentials; Plant Cells; Signal Transduction
PubMed: 21955597
DOI: 10.1111/j.1742-4658.2011.08370.x -
Journal of Chemical Information and... Sep 2021Herein, it is shown how anion recognition in highly polar solvents by neutral metal-free receptors is feasible when multiple hydrogen bonding and anion-π interactions...
Herein, it is shown how anion recognition in highly polar solvents by neutral metal-free receptors is feasible when multiple hydrogen bonding and anion-π interactions are suitably combined. A neutral aromatic molecular tweezer functionalized with azo groups is shown to merge these two kinds of interactions in a unique system and its efficiency as an anion catcher in water is evaluated using first-principles quantum methods. Theoretical calculations unequivocally prove the high thermodynamic stability in water of a model anion, bromide, captured within the tweezer's cavity. Thus, static calculations indicate anion-tweezer interaction energies within the range of covalent or ionic bonds and stability constants in water of more than 10 orders of magnitude. First-principles molecular dynamics calculations also corroborate the stability through the time of the anion-tweezer complex in water. It shows that the anion is always found within the tweezer's cavity due to the combination of the tweezer-anion interactions plus a hydrogen bond between the anion and a water molecule that is inside the tweezer's cavity.
Topics: Anions; Hydrogen Bonding; Solvents; Thermodynamics; Water
PubMed: 34396775
DOI: 10.1021/acs.jcim.1c00595 -
ELife Jul 2021Fluc family fluoride channels protect microbes against ambient environmental fluoride by undermining the cytoplasmic accumulation of this toxic halide. These proteins...
Fluc family fluoride channels protect microbes against ambient environmental fluoride by undermining the cytoplasmic accumulation of this toxic halide. These proteins are structurally idiosyncratic, and thus the permeation pathway and mechanism have no analogy in other known ion channels. Although fluoride-binding sites were identified in previous structural studies, it was not evident how these ions access aqueous solution, and the molecular determinants of anion recognition and selectivity have not been elucidated. Using x-ray crystallography, planar bilayer electrophysiology, and liposome-based assays, we identified additional binding sites along the permeation pathway. We used this information to develop an oriented system for planar lipid bilayer electrophysiology and observed anion block at one of these sites, revealing insights into the mechanism of anion recognition. We propose a permeation mechanism involving alternating occupancy of anion-binding sites that are fully assembled only as the substrate approaches.
Topics: Anions; Bacterial Proteins; Binding Sites; Biophysical Phenomena; Crystallography, X-Ray; Electrophysiology; Fluorides; Glutamic Acid; Ion Channels; Models, Molecular; Protein Conformation
PubMed: 34250906
DOI: 10.7554/eLife.69482