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Molecules (Basel, Switzerland) Dec 2020Lanthanide complexes have been developed and are reported herein. These complexes were derived from a terpyridine-functionalized calix[4]arene ligand, chelated with Tb...
Lanthanide complexes have been developed and are reported herein. These complexes were derived from a terpyridine-functionalized calix[4]arene ligand, chelated with Tb and Eu. Synthesis of these complexes was achieved in two steps from a calix[4]arene derivative: (1) amide coupling of a calix[4]arene bearing carboxylic acid functionalities and (2) metallation with a lanthanide triflate salt. The ligand and its complexes were characterized by NMR (H and C), fluorescence and UV-vis spectroscopy as well as MS. The photophysical properties of these complexes were studied; high molar absorptivity values, modest quantum yields and luminescence lifetimes on the ms timescale were obtained. Anion binding results in a change in the photophysical properties of the complexes. The anion sensing ability of the Tb(III) complex was evaluated via visual detection, UV-vis and fluorescence studies. The sensor was found to be responsive towards a variety of anions, and large binding constants were obtained for the coordination of anions to the sensor.
Topics: Anions; Biosensing Techniques; Calixarenes; Lanthanoid Series Elements; Ligands; Pyridines; Spectrometry, Fluorescence; Temperature
PubMed: 33375511
DOI: 10.3390/molecules26010087 -
Glycoconjugate Journal Jun 2016Glycomic analyses over the years have revealed that non-vertebrate eukaryotes express oligosaccharides with inorganic and zwitterionic modifications which are either... (Review)
Review
Glycomic analyses over the years have revealed that non-vertebrate eukaryotes express oligosaccharides with inorganic and zwitterionic modifications which are either occurring in different contexts as compared to, or are absent from, mammals. Examples of anionic N-glycans (carrying sulphate or phosphate) are known from amoebae, fungi, molluscs and insects, while zwitterionic modifications by phosphorylcholine, phosphoethanolamine and aminoethylphosphonate occur on N-, O- and lipid-linked glycans from trichomonads, annelids, fungi, molluscs, insects, cestodes and nematodes. For detection of zwitterionic and anionic glycans, mass spectrometry has been a key method, but their ionic character affects the preparation and purification; therefore, as part of a glycomic strategy, the possibility of their presence must be considered in advance. On the other hand, their ionisation and fragmentation in positive and negative ion mode mass spectrometry as well as specific chemical or enzymatic treatments can prove diagnostic to their analysis. In our laboratory, we combine solid-phase extraction, reversed and normal phase HPLC, MALDI-TOF MS, exoglycosidase digests and hydrofluoric acid treatment to reveal N-glycans modified with anionic and zwitterionic moieties in a wide range of organisms. It is to be anticipated that, as more species are glycomically analysed, zwitterionic and anionic modifications of N-glycans will prove rather widespread. This knowledge is - in the longer term - then the basis for understanding the function of this cornucopia of glycan modifications.
Topics: Amoebozoa; Animals; Anions; Chromatography, High Pressure Liquid; Invertebrates; Polysaccharides; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Static Electricity
PubMed: 26899268
DOI: 10.1007/s10719-016-9650-x -
Electrophoresis Sep 2019The efficient profiling of highly polar and charged metabolites in biological samples remains a huge analytical challenge in metabolomics. Over the last decade, new... (Review)
Review
The efficient profiling of highly polar and charged metabolites in biological samples remains a huge analytical challenge in metabolomics. Over the last decade, new analytical techniques have been developed for the selective and sensitive analysis of polar ionogenic compounds in various matrices. Still, the analysis of such compounds, notably for acidic ionogenic metabolites, remains a challenging endeavor, even more when the available sample size becomes an issue for the total analytical workflow. In this paper, we give an overview of the possibilities of capillary electrophoresis-mass spectrometry (CE-MS) for anionic metabolic profiling by focusing on main methodological developments. Attention is paid to the development of improved separation conditions and new interfacing designs in CE-MS for anionic metabolic profiling. A complete overview of all CE-MS-based methods developed for this purpose is provided in table format (Table 1) which includes information on sample type, separation conditions, mass analyzer and limits of detection (LODs). Selected applications are discussed to show the utility of CE-MS for anionic metabolic profiling, especially for small-volume biological samples. On the basis of the examination of the reported literature in this specific field, we conclude that there is still room for the design of a highly sensitive and reliable CE-MS method for anionic metabolic profiling. A rigorous validation and the availability of standard operating procedures would be highly favorable in order to make CE-MS an alternative, viable analytical technique for metabolomics.
Topics: Animals; Anions; Electrophoresis, Capillary; Humans; Limit of Detection; Mass Spectrometry; Metabolome; Metabolomics; Mice; Rats; Reproducibility of Results
PubMed: 31106868
DOI: 10.1002/elps.201900115 -
Molecules (Basel, Switzerland) Dec 2022Unlike halides, where the kosmotropicity decreases from fluoride to iodide, the kosmotropic nature of halates apparently increases from chlorate to iodate, in spite of...
Unlike halides, where the kosmotropicity decreases from fluoride to iodide, the kosmotropic nature of halates apparently increases from chlorate to iodate, in spite of the lowering in the static ionic polarizability. In this paper, we present an experimental study that confirms the results of previous simulations. The lyotropic nature of aqueous solutions of sodium halates, i.e., NaClO, NaBrO, and NaIO, is investigated through density, conductivity, viscosity, and refractive index measurements as a function of temperature and salt concentration. From the experimental data, we evaluate the activity coefficients and the salt polarizability and assess the anions' nature in terms of kosmotropicity/chaotropicity. The results clearly indicate that iodate behaves as a kosmotrope, while chlorate is a chaotrope, and bromate shows an intermediate nature. This experimental study confirms that, in the case of halates XO, the kosmotropic-chaotropic ranking reverses with respect to halides. We also discuss and revisit the role of the anion's polarizability in the interpretation of Hofmeister phenomena.
Topics: Anions; Chlorates; Water; Sodium Chloride; Temperature; Iodates
PubMed: 36500616
DOI: 10.3390/molecules27238519 -
Biophysical Journal Mar 2011ClC-4 is a secondary active transporter that exchanges Cl(-) ions and H(+) with a 2:1 stoichiometry. In external SCN(-), ClC-4 becomes uncoupled and transports anions...
ClC-4 is a secondary active transporter that exchanges Cl(-) ions and H(+) with a 2:1 stoichiometry. In external SCN(-), ClC-4 becomes uncoupled and transports anions with high unitary transport rate. Upon voltage steps, the number of active transporters varies in a time-dependent manner, resembling voltage-dependent gating of ion channels. We here investigated modification of the voltage dependence of uncoupled ClC-4 by protons and anions to quantify association of substrates with the transporter. External acidification shifts voltage dependence of ClC-4 transport to more positive potentials and leads to reduced transport currents. Internal pH changes had less pronounced effects. Uncoupled ClC-4 transport is facilitated by elevated external [SCN(-)] but impaired by internal Cl(-) and I(-). Block by internal anions indicates the existence of an internal anion-binding site with high affinity that is not present in ClC channels. The voltage dependence of ClC-4 coupled transport is modulated by external protons and internal Cl(-) in a manner similar to what is observed under uncoupling conditions. Our data illustrate functional differences but also similarities between ClC channels and transporters.
Topics: Anions; Chloride Channels; Electricity; Extracellular Space; HEK293 Cells; Humans; Hydrogen-Ion Concentration; Intracellular Space; Ion Channel Gating; Protons
PubMed: 21354396
DOI: 10.1016/j.bpj.2011.01.045 -
Molecular Pharmacology May 2022Formed by the choroid plexus epithelial (CPE) cells, the blood-cerebrospinal fluid barrier (BCSFB) plays an active role in removing drugs, toxins, and metabolic wastes...
Formed by the choroid plexus epithelial (CPE) cells, the blood-cerebrospinal fluid barrier (BCSFB) plays an active role in removing drugs, toxins, and metabolic wastes from the brain. Several organic cation and anion transporters are expressed in the CPE cells, but how they functionally mediate transepithelial transport of organic cations and anions remain unclear. In this study, we visualized the transcellular transport of fluorescent organic cation and organic anion probes using live tissue imaging in freshly isolated mouse choroid plexuses (CPs). The cationic probe, 4-[4-(dimethylamino)phenyl]-1-methylpyridinium iodide (IDT307) was transported into CPE cells at the apical membrane and highly accumulated in mitochondria. Consistent with the lack of expression of organic cation efflux transporters, there was little efflux of IDT307 into the blood capillary space. Furthermore, IDT307 uptake and intracellular accumulation was attenuated by approximately 70% in CP tissues from mice with targeted deletion of the plasma membrane monoamine transporter (Pmat). In contrast, the anionic probe fluorescein-methotrexate (FL-MTX) was rapidly transported across the CPE cells into the capillary space with little intracellular accumulation. Rifampicin, an inhibitor of organic anion transporting polypeptides (OATPs), completely blocked FL-MTX uptake into the CPE cells whereas MK-571, a pan-inhibitor of multidrug resistance associated proteins (MRPs), abolished basolateral efflux of FL-MTX. In summary, our results suggest distinct transcellular transport pathways for organic cations and anions at the BCSFB and reveal a pivotal role of PMAT, OATP and MRP transporters in organic cation and anion transport at the blood-cerebrospinal fluid interface. SIGNIFICANCE STATEMENT: Live tissue imaging revealed that while organic cations are transported from the cerebrospinal fluid (CSF) into the choroid plexus epithelial cells by plasma membrane monoamine transporter without efflux into the blood, amphipathic anions in the CSF are efficiently transported across the BCSFB through the collaborated function of apical organic anion transporting polypeptides and basolateral multidrug resistance associated proteins. These findings contribute to a mechanistic understanding of the molecular and cellular pathways for choroid plexus clearance of solutes from the brain.
Topics: Animals; Anions; Blood-Brain Barrier; Cations; Choroid Plexus; Membrane Transport Proteins; Mice; Multidrug Resistance-Associated Proteins; Organic Anion Transporters; Peptides; Transcytosis
PubMed: 35193935
DOI: 10.1124/molpharm.121.000439 -
Journal of the American Chemical Society Aug 2022Chalcogen bonding (ChB) is rapidly rising to prominence in supramolecular chemistry as a powerful sigma (σ)-hole-based noncovalent interaction, especially for...
Chalcogen bonding (ChB) is rapidly rising to prominence in supramolecular chemistry as a powerful sigma (σ)-hole-based noncovalent interaction, especially for applications in the field of molecular recognition. Recent studies have demonstrated ChB donor strength and potency to be remarkably sensitive to local electronic environments, including redox-switchable on/off anion binding and sensing capability. Influencing the unique electronic and geometric environment sensitivity of ChB interactions through simultaneous cobound metal cation recognition, herein, we present the first potassium chloride-selective heteroditopic ion-pair receptor. The direct conjugation of benzo-15-crown-5 ether (B15C5) appendages to Te centers in a bis-tellurotriazole framework facilitates alkali metal halide (MX) ion-pair binding through the formation of a cofacial intramolecular bis-B15C5 M (M = K, Rb, Cs) sandwich complex and bidentate ChB···X formation. Extensive quantitative H NMR ion-pair affinity titration experiments, solid-liquid and liquid-liquid extraction, and U-tube transport studies all demonstrate unprecedented KCl selectivity over all other group 1 metal chlorides. It is demonstrated that the origin of the receptor's ion-pair binding cooperativity and KCl selectivity arises from an electronic polarization of the ChB donors induced by the cobound alkali metal cation. Importantly, the magnitude of this switch on Te-centered electrophilicity, and therefore anion-binding affinity, is shown to correlate with the inherent Lewis acidity of the alkali metal cation. Extensive computational DFT investigations corroborated the experimental alkali metal cation-anion ion-pair binding observations for halides and oxoanions.
Topics: Anions; Cations; Chalcogens; Chlorides; Metals, Alkali; Potassium Chloride
PubMed: 35930460
DOI: 10.1021/jacs.2c05333 -
Chemical Communications (Cambridge,... Mar 2020A novel class of transmembrane anion carriers, the click-tambjamines, display remarkable anionophoric activities in model liposomes and living cells. The versatility of...
A novel class of transmembrane anion carriers, the click-tambjamines, display remarkable anionophoric activities in model liposomes and living cells. The versatility of this building block for the generation of molecular diversity offers promise to develop future drugs based on this design.
Topics: A549 Cells; Anions; Antineoplastic Agents; Cell Line; Cell Proliferation; Crystallography, X-Ray; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Ion Transport; Liposomes; MCF-7 Cells; Models, Molecular; Molecular Structure; Pyrroles; Structure-Activity Relationship
PubMed: 32073062
DOI: 10.1039/d0cc00643b -
Microbiological Reviews Mar 1990This article discusses the physiological, biochemical, and molecular properties of bacterial anion-exchange reactions, with a particular focus on a family of phosphate... (Review)
Review
This article discusses the physiological, biochemical, and molecular properties of bacterial anion-exchange reactions, with a particular focus on a family of phosphate (Pi)-linked antiporters that accept as their primary substrates sugar phosphates such as glucose 6-phosphate (G6P), mannose 6-phosphate, or glycerol 3-phosphate. Pi-linked antiporters may be found in both gram-positive and gram-negative cells. As their name suggests, these exchange proteins accept both inorganic and organic phosphates, but the two classes of substrate interact very differently with the protein. Thus, Pi is always accepted with a relatively low affinity, and when it participates in exchange, it is always taken as the monovalent anion. By contrast, when the high-affinity organic phosphates are used, these same systems fail to discriminate between monovalent and divalent forms. Tests of heterologous exchange (e.g., Pi: G6P) indicate that these proteins have a bifunctional active site that accepts a pair of negative charges, whether as two monovalent anions or as a single divalent anion. For this reason, exchange stoichiometry moves between limits of 2:1 and 2:2, according to the ratio of mono- and divalent substrates at either membrane surface. Since G6P has a pK2 within the physiological range (pK of 6.1), this predicts a novel reaction sequence in vivo because internal pH is more alkaline than external pH. Accordingly, one expects an asymmetric exchange as two monovalent G6P anions from the relatively acidic exterior move against a single divalent G6P from the alkaline interior. In this way an otherwise futile self-exchange of G6P can be biased towards a net inward flux driven (indirectly) by the pH gradient. Despite the biochemical complexity exhibited by Pi-linked antiporters, they resemble all other secondary carriers at a molecular level and show a likely topology in which two sets of six transmembrane alpha-helices are connected by a central hydrophilic loop. Speculations on the derivation of this common form suggest a limited number of structural models to accommodate such proteins. Three such models are presented.
Topics: Anions; Bacteria; Biological Transport, Active; Cell Membrane; Ion Exchange; Models, Biological
PubMed: 2181257
DOI: 10.1128/mr.54.1.1-17.1990 -
ACS Sensors Aug 2023We report here a small library of a new type of acyclic squaramide receptors (-) as selective ionophores for the detection of ketoprofen and naproxen anions (KF and NS,...
We report here a small library of a new type of acyclic squaramide receptors (-) as selective ionophores for the detection of ketoprofen and naproxen anions (KF and NS, respectively) in aqueous media. H NMR binding studies show a high affinity of these squaramide receptors toward KF and NS, suggesting the formation of H-bonds between the two guests and the receptors through indole and -NH groups. Compounds - have been tested as ionophores for the detection of KF and NS inside solvent PVC-based polymeric membranes. The optimal membrane compositions were established through the careful variation of the ligand/tridodecylmethylammonium chloride (TDMACl) anion-exchanger ratio. All of the tested acyclic squaramide receptors - have high affinity toward KF and NS and anti-Hofmeister selectivity, with and showing the highest sensitivity and selectivity to NS. The utility of the developed sensors for a high precision detection of KF in pharmaceutical compositions with low relative errors of analysis (RSD, 0.99-1.4%) and recoveries, %, in the range 95.1-111.8% has been demonstrated. Additionally, the chemometric approach has been involved to effectively discriminate between the structurally very similar KF and NS, and the possibility of detecting these analytes at concentrations as low as 0.07 μM with of 0.947 and at 0.15 μM with of 0.919 for NS and KF, respectively, was shown.
Topics: Ionophores; Anions; Quinine
PubMed: 37530141
DOI: 10.1021/acssensors.3c00981