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1
Powell, J. J., R. Jugdaohsingh, and R. P. H. Thompson. "The regulation of mineral absorption in the gastrointestinal tract." Proceedings of the Nutrition Society 58, no. 1 (1999): 147–53. http://dx.doi.org/10.1079/pns19990020.
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The absorption of metal ions in the mammalian single-stomached gut is fortunately highly selective, and both luminal and tissue regulation occur. Initially, assimilation of metal ions in an available form is facilitated by the intestinal secretions, chiefly soluble mucus (mucin) that retards hydrolysis of ions such as Cu, Fe and Zn. Metal ions then bind and traverse the mucosally-adherent mucus layer with an efficiency M+> M2+> M3+. At the mucosa Fe3+is probably uniquely reduced to Fe2+, and all divalent cations (including Fe2+) are transported by a membrane protein (such as divalent cation transporter 1) into the cell. This minimizes absorption of toxic trivalent metals (e.g. A13+). Intracellular metal-binding molecules (such as mobilferrin) may be present at the intracellular side of the apical membrane, anchored to a transmembrane protein such as an integrin complex. This mobilferrin would receive the metal ion from divalent cation transporter 1 and, with part of the integrin molecule, transport the metal to the cytosol for safe sequestration in a larger complex such as ferritin or‘paraferritin’. β2-Microglobulin and HFE (previously termed human leucocyte antigen H) may be involved in stabilizing metal mobilferrin-integrin to form this latter complex. Finally, a systemic metal-binding protein such as transferrin may enter the antiluminal (basolateral) side of the cell for binding of the sequestered metal ion and delivery to the circulation. Regulatory proteins, such as HFE, may determine the degree of ion transport from intestinal cells to the circulation. Gradients in pH and perhaps pCa or even pNa could allow the switching of ions between the different transporters throughout this mechanism.
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Huang, Hao, Joel N. Bogstie, and Hans J. Vogel. "Biophysical and structural studies of the human calcium- and integrin-binding protein family: understanding their functional similarities and differences." Biochemistry and Cell Biology 90, no. 5 (2012): 646–56. http://dx.doi.org/10.1139/o2012-021.
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The human calcium- and integrin-binding protein 1 (CIB1) plays important roles in various cellular functions. In this study, three other members of this protein family (CIB2–4: CIB2, CIB3, and CIB4) were purified and subsequently characterized using biophysical and structural approaches. As expected from sequence alignments, CIB2–4 were shown to bind calcium (Ca2+) and magnesium (Mg2+) ions. Binding of Ca2+ or Mg2+ ions changes the secondary structure of CIB2–4 and the exposure of hydrophobic surface area. Ca2+ and Mg2+ ions also stabilize the tertiary structures for CIB2 and CIB3. Through in vitro binding experiments, we show that CIB2 can interact with the integrin αIIb cytoplasmic domain and the integrin α7b membrane-proximal fragment. Fluorescence experiments using a 7-azatryptophan labeled peptide demonstrate that CIB2, CIB3, and CIB4 are binding partners for the integrin αIIb subunit, which suggests that they are potentially involved in regulating integrin αIIb subunit activation. The distinct responses of αIIb to the different CIB3 and CIB4 metal (Ca2+ and Mg2+) binding states imply a potential connection between the calcium and integrin signaling pathways.
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Schumacher, Stephanie, Dirk Dedden, Roberto Vazquez Nunez та ін. "Structural insights into integrin α5β1 opening by fibronectin ligand". Science Advances 7, № 19 (2021): eabe9716. http://dx.doi.org/10.1126/sciadv.abe9716.
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Integrin α5β1 is a major fibronectin receptor critical for cell migration. Upon complex formation, fibronectin and α5β1 undergo conformational changes. While this is key for cell-tissue connections, its mechanism is unknown. Here, we report cryo–electron microscopy structures of native human α5β1 with fibronectin to 3.1-angstrom resolution, and in its resting state to 4.6-angstrom resolution. The α5β1-fibronectin complex revealed simultaneous interactions at the arginine-glycine-aspartate loop, the synergy site, and a newly identified binding site proximal to adjacent to metal ion–dependent adhesion site, inducing the translocation of helix α1 to secure integrin opening. Resting α5β1 adopts an incompletely bent conformation, challenging the model of integrin sharp bending inhibiting ligand binding. Our biochemical and structural analyses showed that affinity of α5β1 for fibronectin is increased with manganese ions (Mn2+) while adopting the half-bent conformation, indicating that ligand-binding affinity does not depend on conformation, and α5β1 opening is induced by ligand-binding.
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Ajroud, Kaouther, Takashi Sugimori, Wolfgang H. Goldmann, Dahmani M. Fathallah, Jian-Ping Xiong, and M. Amin Arnaout. "Binding Affinity of Metal Ions to the CD11b A-domain Is Regulated by Integrin Activation and Ligands." Journal of Biological Chemistry 279, no. 24 (2004): 25483–88. http://dx.doi.org/10.1074/jbc.m402901200.
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Michalska, Agnieszka, Sebastian Golczak, Krzysztof Langer, and Jerzy Langer. "Micro- and Nanostructured Polyaniline for Instant Identification of Metal Ions in Solution." Nanomaterials 9, no. 2 (2019): 231. http://dx.doi.org/10.3390/nano9020231.
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The unique properties of nanomaterials enable the creation new analytical devices. Polyaniline (PANI) micro- and nanofiber network, freestanding in the gap between two gold microelectrodes, has been used in a new nanodetector for metal ions in solutions. The gold electrodes were modified with the aid of alkanethiols, forming a self-assembled monolayer (SAM), which is able to block the ion current flow, but also to interact with metal ions when specific functional molecules are incorporated into the layer. The electric field of the trapped metal ions induces change of the electrical conductivity of polyaniline nanofibers in vicinity. A small injected sample (75 μL) of a solution of salt (about 0.5 μg of salt) was enough to induce a reproducible change in the electrical conductivity of polyaniline nano-network, which was registered as a function of time within 10–20 s. The response was proportional to the concentration of ions. It also depends on properties of ions, e.g., the ionic radius, which allows for identification of metal ions by analyzing the parameters of the signal: the retention time (RT), half width (HW), amplitude (A) and integral intensity (INT). The advantage of the new device is the instant responsiveness and easy operation, but also the simple construction based on organic (polymer) technology. The system is “open”—when learned and calibrated adequately, other metal ions can be analyzed. The nanodetector can be used in cases where monitoring of the presence and concentration of metal ions is important.
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Shamanin V.I. and Tarbokov V.A. "Multicharged metal ions generation in a self-magnetically insulated ion diode." Technical Physics Letters 49, no. 5 (2023): 63. http://dx.doi.org/10.21883/tpl.2023.05.56032.19507.
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A self-magnetically insulated ion diode was used to produce a pulsed beam of metallic ions from explosion emission plasma. The ratio of integral transferred charge for the Al, Ti and Mo ions amounted to at least 63% to the total beam charge. The ion diode had design features, which consisted in a bladed cathode and a removable perforated anode overlay made of VT-8 alloy. Analysis of the charge to mass characteristics of beam ions and the ion current density waveforms by the time of flight methodic with use of a Faraday cup showed the content of aluminum and titanium ions in the third to fourth states of ionization. Keywords: ion diode, metal ions, magnetic spectrometer, track detector CR-39.
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Kavitha, Govindarajan, Parasuraman Vijaya Rohini, and Sunkubangaru Sudarsan Alwar. "Potentiometric Studies of Binary Complexes of Transition Metal Ions with Lauric Acid." Oriental Journal of Chemistry 34, no. 5 (2018): 2681–84. http://dx.doi.org/10.13005/ojc/340564.
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The potentials of binary complexes of the Lauric acid ligand with various biologically vital divalent metal ions such as Mn(II), Co(II), Ni(II), Cu(II)and Zn(II) have been studied in 50% DMSO-water mixture at constant ionic strength by Bjerrum method. Hydrogen ion concentrations were measured and the formation of binary complexes was inferred from the corresponding potentiometric pH-titration curves. The metal to ligand mole ratio was maintained at 1:5 to facilitate the maximum number of ligands to the metal ion. The dissociation constant has been determined by the half-integral method and pointwise method and were found in good agreement with each other. The Metal-Lauric acid stability constants have been calculated and compared with the results.
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Gupta, Neelmani, Murari Prasad, Nidhi Singhal, and Vineet Kumar. "Modeling the Adsorption Kinetics of Divalent Metal Ions onto Pyrophyllite Using the Integral Method." Industrial & Engineering Chemistry Research 48, no. 4 (2009): 2125–28. http://dx.doi.org/10.1021/ie800975m.
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Singhal, Nidhi, Murari Prasad, Neelmani Gupta, and Vineet Kumar. "Modeling the sorption kinetics of divalent metal ions onto mineral adsorbent using integral method." Journal of Colloid and Interface Science 313, no. 2 (2007): 423–27. http://dx.doi.org/10.1016/j.jcis.2007.04.068.
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Kolmas, Joanna, Ewa Groszyk, and Dagmara Kwiatkowska-Różycka. "Substituted Hydroxyapatites with Antibacterial Properties." BioMed Research International 2014 (2014): 1–15. http://dx.doi.org/10.1155/2014/178123.
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Reconstructive surgery is presently struggling with the problem of infections located within implantation biomaterials. Of course, the best antibacterial protection is antibiotic therapy. However, oral antibiotic therapy is sometimes ineffective, while administering an antibiotic at the location of infection is often associated with an unfavourable ratio of dosage efficiency and toxic effect. Thus, the present study aims to find a new factor which may improve antibacterial activity while also presenting low toxicity to the human cells. Such factors are usually implemented along with the implant itself and may be an integral part of it. Many recent studies have focused on inorganic factors, such as metal nanoparticles, salts, and metal oxides. The advantages of inorganic factors include the ease with which they can be combined with ceramic and polymeric biomaterials. The following review focuses on hydroxyapatites substituted with ions with antibacterial properties. It considers materials that have already been applied in regenerative medicine (e.g., hydroxyapatites with silver ions) and those that are only at the preliminary stage of research and which could potentially be used in implantology or dentistry. We present methods for the synthesis of modified apatites and the antibacterial mechanisms of various ions as well as their antibacterial efficiency.
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Murcia, Marta, Marketa Jirouskova, Jihong Li, Barry S. Coller та Filizola Marta. "Equilibrium and Non-Equilibrium Molecular Dynamics Simulations Provide Potential Mechanisms for the Loss of Ligand Binding to αIIbβ3 Mutants Affecting the Ligand-Induced Metal Binding Site (LIMBS)." Blood 108, № 11 (2006): 1805. http://dx.doi.org/10.1182/blood.v108.11.1805.1805.
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Abstract Although the role of the β3 MIDAS metal ion in ligand binding to αIIbβ3 is well established, serving as the site of interaction of the ligand Asp residue, the role of the nearby LIMBS metal ion is less well defined. Previous studies suggested a role for the LIMBS in ligand binding. We confirmed this by showing that HEK293 cells expressing normal αIIbβ3 adhered to both immobilized fibrinogen and the RGD-containing venom echistatin in the presence of either Mg++/Ca++ or Mn++, whereas two different αIIbβ3 LIMBS mutants (β3 N215A and D217A) failed to adhere to either protein. In addition, we found that both mutations also increased the binding of mAb AP5, which recognizes a ligand-induced binding site (LIBS) in the β3 PSI domain (normal 7±4% vs N215A 46±12% and D217A 41±20% of mAb anti-αIIb (HIP8) binding; mean±SD, n=6, p<0.05 for both), indicating that the mutations caused allosteric changes in the conformation of the receptor. To define the mechanism(s) by which the LIMBS mutants affect ligand binding, we carried out equilibrium and non-equilibrium (steered) molecular dynamics (MD) simulations of the cyclic peptide ligand eptifibatide in complex with either the fully hydrated normal αIIbβ3 integrin headpiece (PDB 1TY6) or the equivalent β3 D217A mutant, with and without the LIMBS metal ion. Simulations were carried out using the GROMACS package with the OPLS all-atom force-field. During the simulation, the hybrid domain of the D217A mutant demonstrated greater structural fluctuations than the normal αIIbβ3. Although Craig et al. have reported the appearance of a new contact between the RGD peptide ligand Asp carboxyl and the LIMBS metal ion in αVβ3 after 10 ps of a 1 ns simulation, we did not observe the appearance of such an interaction between the eptifibatide carboxyl and the normal αIIbβ3 LIMBS metal ion even after 20 ns. We did, however, observe such an interaction with the LIMBS metal ion in the D217A mutant. This interaction was facilitated by the movement of the LIMBS ~ 2 Å closer to the MIDAS, and was accompanied by rearrangements of the LIMBS coordinating residues D158 and N215. When the D217A mutant simulation was performed in the absence of the LIMBS metal ion, changes in the orientation of E220 were also observed. The D217A mutant demonstrated increased fluctuations in the C177–C184 specificity-determining loop (SDL), which has been implicated in ligand binding, and decreased fluctuations in K209. Steered MD were used to investigate the pulling forces required to unbind eptifibatide from its binding site. Notably, although the unbinding force decreased modestly when the LIMBS metal ion was removed, it required removal of both the LIMBS and MIDAS metal ions to effect a marked reduction in unbinding force. The binding free energies of the association of the αIIb and β3 subunits were also calculated, and the D217A mutant in the presence of the LIMBS metal ion demonstrated much tighter binding than normal integrin αIIbβ3 (ΔGb −162±6 vs −119±6 Kcal/mol; mean±SD; n=500). We conclude that the LIMBS plays a crucial role in ligand binding to αIIbβ3, perhaps by virtue of its effects on the coordination of the MIDAS, the accentuated mobility of specific domains (e.g., the SDL and the hybrid domains), and/or the number and strength of contacts between αIIb and β3.
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Athanasellis, Giorgos, Georgia Zahariou, Stefanos Kikionis, Olga Igglessi-Markopoulou, and John Markopoulos. "Coordination Behavior of 3-Ethoxycarbonyltetronic Acid towards Cu(II) and Co(II) Metal Ions." Bioinorganic Chemistry and Applications 2008 (2008): 1–6. http://dx.doi.org/10.1155/2008/547915.
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Tetronic acids, 4-hydroxy-5H-furan-2-ones, constitute a class of heterocyclic compounds with potent biological and pharmacological activity. Theβ,β′-tricarbonyl moiety plays an integral role in biological systems and forms a variety of metal complexes. In this report, we present the complexation reactions of 3-ethoxycarbonyl tetronic acids with acetates and chlorides of Cu(II) and Co(II). These complexes have been studied by means of EPR spectroscopy and magnetic susceptibility measurements. From the obtained results, a preliminary complexation mode of the ligand is proposed.
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Linsdell, Paul. "Metal bridges to probe membrane ion channel structure and function." Biomolecular Concepts 6, no. 3 (2015): 191–203. http://dx.doi.org/10.1515/bmc-2015-0013.
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AbstractIon channels are integral membrane proteins that undergo important conformational changes as they open and close to control transmembrane flux of different ions. The molecular underpinnings of these dynamic conformational rearrangements are difficult to ascertain using current structural methods. Several functional approaches have been used to understand two- and three-dimensional dynamic structures of ion channels, based on the reactivity of the cysteine side-chain. Two-dimensional structural rearrangements, such as changes in the accessibility of different parts of the channel protein to the bulk solution on either side of the membrane, are used to define movements within the permeation pathway, such as those that open and close ion channel gates. Three-dimensional rearrangements – in which two different parts of the channel protein change their proximity during conformational changes – are probed by cross-linking or bridging together two cysteine side-chains. Particularly useful in this regard are so-called metal bridges formed when two or more cysteine side-chains form a high-affinity binding site for metal ions such as Cd2+ or Zn2+. This review describes the use of these different techniques for the study of ion channel dynamic structure and function, including a comprehensive review of the different kinds of conformational rearrangements that have been studied in different channel types via the identification of intra-molecular metal bridges. Factors that influence the affinities and conformational sensitivities of these metal bridges, as well as the kinds of structural inferences that can be drawn from these studies, are also discussed.
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Jin, Tao, and Rong Chang Zeng. "Structure and Infrared Radiation Properties of Metal Oxides-Doped Cordierites Using Graded Sintering Synthesis." Advanced Materials Research 311-313 (August 2011): 140–44. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.140.
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The infrared radiation materials of transition metal oxides doped cordierite systems are synthesized using graded solid phase sintering. And the infrared radiation properties are investigated by means of X-ray diffraction, infrared spectrometry and scanning electron microscope. The results show that new compounds are developed during graded heat treatment from 900 °C to 1250 °C. The spinel phases produced are the main crystal material, and the different doped ions and impurity carbon cause the new phases, to different degree defect in this system ,which types can be classified into: (Mg,Zn,□)Fe2O4, (Mg,Zn,Co,□)Al2O4, (Co,□)Cr2O4,SiC etc., The main diffraction peaks of new phases formed are positioned at the zone (2θ) between 35.227o and 36.837o, and has stretching vibration peaks. And the main infrared absorption peaks located at the low wave number zone indicate to some degree deviation under different doped ions. The doped cordierites have infrared emissivity superior to that prepared with the conventional one-step synthesis. The full wave band integral emissivity of the spinel phases ranged between 0.88 and 0.94 at ambient temperature.
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Fedenko, Volodymyr S., Marco Landi, and Sergiy A. Shemet. "Metallophenolomics: A Novel Integrated Approach to Study Complexation of Plant Phenolics with Metal/Metalloid Ions." International Journal of Molecular Sciences 23, no. 19 (2022): 11370. http://dx.doi.org/10.3390/ijms231911370.
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Plant adaptive strategies have been shaped during evolutionary development in the constant interaction with a plethora of environmental factors, including the presence of metals/metalloids in the environment. Among adaptive reactions against either the excess of trace elements or toxic doses of non-essential elements, their complexation with molecular endogenous ligands, including phenolics, has received increasing attention. Currently, the complexation of phenolics with metal(loid)s is a topic of intensive studies in different scientific fields. In spite of the numerous studies on their chelating capacity, the systemic analysis of phenolics as plant ligands has not been performed yet. Such a systematizing can be performed based on the modern approach of metallomics as an integral biometal science, which in turn has been differentiated into subgroups according to the nature of the bioligands. In this regard, the present review summarizes phenolics–metal(loid)s’ interactions using the metallomic approach. Experimental results on the chelating activity of representative compounds from different phenolic subgroups in vitro and in vivo are systematized. General properties of phenolic ligands and specific properties of anthocyanins are revealed. The novel concept of metallophenolomics is proposed, as a ligand-oriented subgroup of metallomics, which is an integrated approach to study phenolics–metal(loid)s’ complexations. The research subjects of metallophenolomics are outlined according to the methodology of metallomic studies, including mission-oriented biometal sciences (environmental sciences, food sciences and nutrition, medicine, cosmetology, coloration technologies, chemical sciences, material sciences, solar cell sciences). Metallophenolomics opens new prospects to unite multidisciplinary investigations of phenolic–metal(loid) interactions.
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Kurant, V. Z., та V. O. Khomenchuk. "ВПЛИВ ІОНІВ МАНГАНУ, ЦИНКУ, КУПРУМУ ТА ПЛЮМБУМУ НА ВМІСТ ВІЛЬНИХ АМІНОКИСЛОТ В ОРГАНІЗМІ КОРОПА". Scientific Issue Ternopil Volodymyr Hnatiuk National Pedagogical University. Series: Biology 75, № 1 (2019): 28–42. http://dx.doi.org/10.25128/2078-2357.19.1.4.
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The influence of ions of Manganese, Zinc, Copper and Lead in two concentrations, which corresponded to 2 and 5 MPC, on the content of free amino acids in the carp organism was studied. It is shown, that free amino acids are compounds, that are actively used in the energy supply of fish organisms. Their metabolism is one of the factors, that provides biochemical adaptation of fish to the changes of the conditions in the aquatic environment. The leading role in this process in carp organism have glycine, the content of which in the muscles of the control fish is quite high. It exceeds all other concentrations of amino acids in this tissue, and when exposed to the organism of fish, the ions of the investigated metals decreases to the greatest extent. Among other amino acids, it should be noted the growth both in the muscles and in the liver of experimental fish the amount of sulfur-containing. An important role in the detoxification of ammonia, which is formed under the influence on the organism of carp the elevated metal concentrations, belongs to aspartic and glutamic acids. In our studies, the content of free amino acids in the liver and muscle of fish is reduced by the action of metal ions, which may indicate an active involvement of aspartic and glutamic acid in the processes of detoxification of these ions. In general, the dynamics of free amino acids in carp tissues reflects the general tendencies of metabolism in its organism. Oxidation catabolism of amino acids of skeletal muscle and liver of fish is an important part of the integral physiological and biochemical mechanism, which provides energy homeostasis in their organism in conditions of intoxication.
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Knöpfel, Martin, Georg Schulthess, Felix Funk, and Helmut Hauser. "Characterization of an Integral Protein of the Brush Border Membrane Mediating the Transport of Divalent Metal Ions." Biophysical Journal 79, no. 2 (2000): 874–84. http://dx.doi.org/10.1016/s0006-3495(00)76343-0.
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Mollaamin, Fatemeh, and Majid Monajjemi. "Application of DFT/TD-DFT Frameworks in the Drug Delivery Mechanism: Investigation of Chelated Bisphosphonate with Transition Metal Cations in Bone Treatment." Chemistry 5, no. 1 (2023): 365–80. http://dx.doi.org/10.3390/chemistry5010027.
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Carbon nanotubes (CNTs) are applied in a drug delivery system, which can be reacted with different structures such biomolecules. Bones have vital functions and are the locations of biochemical reactions in cells that might be exposed various diseases. As different metal ions are integral components of bone tissue with different functions in the physiological cellular medium as well as in bone treatment, they can be used differently as a basis or as a supplement for various materials in the field of bone repair. Therefore, this research aims to represent the recent progress in conjugated bisphosphonate (BP)-divalent transition metal ions of Mn2+, Fe2+, and Co2+ with an emphasis on the properties of interaction with a (6, 6) armchair carbon nanotube as a nanocarrier to exhibit the potential biomedical application of drug delivery. In this article, “CNT” linked to “BP“ of alendronic acid, ibandronic acid, neridronic acid, and pamidronic acid, which are chelated to transition metal cations of Mn2+, Fe2+, and Co2+, was investigated based on DFT insights for obtaining the electron charge density. Transition metals chelating with phosphonate groups, which are large with six O atoms with negative charges, are active in generating chelated complexes with the bisphosphonates [BPs- Mn2+/Fe2+/Co2+] through the status of drug design. In this work, B3LYP/6-311+G(d,p)/lanl2dz we have estimated the susceptibility of CNT for conjugating alendronic acid, ibandronic acid, neridronic acid, and pamidronic acid, which are chelated to transition metal cations of Mn2+, Fe2+, and Co2+ through NMR, NQR, IR, UV-VIS spectroscopy, and HOMO-LUMO analysis. Finally, the obtained results have confirmed that the possibility of applying CNT and BPs of alendronic acid, ibandronic acid, neridronic acid, and pamidronic acid becomes suitable in transition metal chelating for delivery application. The calculated HOMO–LUMO energy gaps for BPs of alendronic acid, ibandronic acid, neridronic acid, and pamidronic acid at the B3LYP/6-311+G (d, p) level have revealed that the energy gap reflects the chemical activity of the molecule.
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Zhu, Jieqing, Won-Seok Choi, Joshua G. McCoy та ін. "Structure-Guided Design of A Novel High Affinity Integrin αIIbβ3 Receptor Antagonist (RUC-2) That Displaces Mg2+ From the β3 MIDAS",. Blood 118, № 21 (2011): 3255. http://dx.doi.org/10.1182/blood.v118.21.3255.3255.
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Abstract Abstract 3255 The platelet αIIbβ3 integrin receptor plays a central role in hemostasis and thrombosis. Small molecule inhibitors of αIIbβ3 based on the RGD cell recognition sequence block ligand binding by interacting with αIIb D224 via their positively-charged (R-like) group and coordinating the Mg2+ ion in the metal ion adhesion site (MIDAS) via their carboxyl (D-like) group. We recently reported a novel inhibitor of αIIbβ3 (RUC-1) that binds exclusively to αIIb and we now report the structure-based design and synthesis of RUC-2 [2-amino-N-(3-(5-oxo-7-(piperazin-1-yl)-5H-[1,3,4]thiadiazolo[3,2-a]pyrimidin-2-yl)phenyl)acetamide; MW 385], a RUC-1 derivative with ∼100-fold higher affinity and an IC50= ∼90 nM for ADP-induced platelet aggregation. RUC-2, like RUC-1 shows specificity for αIIbβ3 compared to αVβ3 and produces much less exposure of the β3 LIBS1 epitope than does eptifibatide (eptifibatide=100%, untreated platelets=22±3 %; RUC-2=21±3%). RUC-2 also produces less of a global conformational change in αIIbβ3 compared to eptifibatide as measured by dynamic light scattering, gel permeation chromatography, and electron microscopic imaging of αIIbβ3 in nanodiscs. X-ray crystallography of RUC-2 soaked into the αIIbβ3 headpiece in 1 mM Ca2+ and 5 mM Mg2+ at 2.6 Å revealed that RUC-2 binds to αIIb much the way RUC-1 does, but in addition it binds to one of the sidechain carboxyl oxygens of the β3 MIDAS residue Glu-220, thus displacing Mg2+ from the MIDAS. When RUC-2 was soaked into the crystal in the presence of 20 mM Mg2+, however, the Mg2+ was identified in the MIDAS and RUC-2 was absent from the pocket. Molecular dynamics simulations were in accord with the X-ray crystallographic data. Support for competition between RUC-2 and Mg2+ for binding to the MIDAS came from studies showing that increasing the Mg2+ concentration significantly decreased RUC-2's ability to inhibit PAC-1 binding to CHO cells expressing αIIbβ3, platelet adhesion to fibrinogen, and thrombin receptor activating peptide-induced platelet aggregation. We conclude that RUC-2 inhibits ligand binding with high affinity and specificity by a novel mechanism in which it competes with Mg2+ for Glu-220, and as such may offer advantages as a therapeutic agent. The binding pocket of RUC-2 in the closed αIIbβ3 headpiece crystal structure. αIIb and β3 are shown as solvent accessible surfaces. Ca2+ ions of SyMBS or ADMIDAS (yellow) are shown as spheres. RUC-2 and selected αIIbβ3 sidechain and backbone atoms are shown as sticks with green (RUC-2), light blue (αIIb), or wheat carbons (β3), red oxygens, blue nitrogens, and yellow sulphurs. Water molecules are small red spheres. Hydrogen and metal coordination bonds are shown as dashed blue lines. Disclosures: Coller: Centocor/Accumetrics/Rockefeller University: Royalty interests in abciximab/VerifyNow assays/RUC-1 and RUC-2.
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DiScipio, Richard G., Pamela J. Daffern, Ingrid U. Schraufstätter та Pragda Sriramarao. "Human Polymorphonuclear Leukocytes Adhere to Complement Factor H Through an Interaction That Involves αMβ2 (CD11b/CD18)". Journal of Immunology 160, № 8 (1998): 4057–66. http://dx.doi.org/10.4049/jimmunol.160.8.4057.
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Abstract The work presented here demonstrates that human complement factor H is an adhesion ligand for human neutrophils but not for eosinophils. The adherence of polymorphonuclear leukocytes (PMNs) to plastic wells coated with factor H depended on divalent metal ions and was augmented by C5a and TNF-α. PMN adhesion to factor H in the presence or absence of C5a was blocked specifically by mAbs against CD11b or CD18. Affinity purification using factor H Sepharose followed by immunoprecipitation using mAbs to various integrin chains identified Mac-1 (CD11b/CD18) as a factor H binding receptor. The presence of surface bound factor H enhanced neutrophil activation resulting in a two- to fivefold increase in the generation of hydrogen peroxide by PMNs stimulated by C5a or TNF-α. When factor H was mixed with PMNs, 1.4 to 3.8-fold more cells adhered to immobilized heparin or chondroitin A. In addition, augmented adhesion of PMNs was measured when factor H, but not HSA or C9, was absorbed to wells that were first coated with heparin or chondroitin A. The adhesion of PMNs to glycosaminoglycan-factor H was blocked by mAbs to CD11b and CD18. These studies demonstrate that factor H is an adhesion molecule for human neutrophils and suggest that the interaction of factor H with glycosaminoglycans may facilitate the tethering of this protein in tissues allowing factor H to serve as a neutrophil adhesion ligand in vivo.
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Gabidulina, Marina K., Sergey Yu Doronin, and Irina V. Kosyreva. "Test means for separate and total determination of heavy metals in aqueous media." Butlerov Communications 57, no. 1 (2019): 101–14. http://dx.doi.org/10.37952/roi-jbc-01/19-57-1-101.
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The classification of the main indicators of the quality of water bodies is considered. The data on controlled chemical indicators are given (content of dissolved oxygen, suspended solids, phenols, petroleum products, etc.) A list of priority hydrochemical water pollutants and the sources of their pollution are presented. The expediency of determining both individual ions of heavy metals (HM) and their complex (integral) indicators is shown by the example of the sum of HMs. The authors summarized existing data on contemporary test methods used for detection and quantitative measurement of the most prominent HM pollutants of aqueous media, namely – Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Mn(II) and Al(III) ions. Concentration of such HM ions can be evaluated by various test means such as indicator papers, detector tubes and polymer plates etc. The main matrices of the test means are considered: cellulose papers, fabrics from artificial and natural fibers, silica gels, xerogels, polymeric materials, etc. The conditions for immobilization and modification of test means (carrying agent, reagent, surfactant, etc.) and principles of analyte determination using the developed test tools (visual and instrumental assessment of the intensity of staining of test forms, determination of the length of staining or bleaching of test tube zones, etc.), as well as some metrological characteristics (detection limit, range of determined contents, relative errors of definitions, etc.) are shown in this article. Detection limits of studied heavy metal ions in aqueous media that can be achieved with proposed test means are as follows: Fe(II) – (0.005-0.01) mg/l; Fe(III) – 0.1 mg/l; Co(II) – (0.02-0.4) mg/l; Ni(II) – (0.1-10) mg/l; Cu(II) – 0.05 mg/l; Mn(II) – 0.03 mg/l; Al(III) – 0.02 mg/l; total concentration of several HM ions – (0.0005-0.001) mg/l.
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Gun'ko, V. M. "Quantum-chemically computed integral characteristics of complex nanomaterials." Himia, Fizika ta Tehnologia Poverhni 12, no. 3 (2021): 157–67. http://dx.doi.org/10.15407/hftp12.03.157.
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Development of theoretical tools to analyze electronic structure of complex nanomaterials depending on features of spatial and chemical organizations of different phases is of interest from both practical and theoretical points of view. Therefore, in this work, an approach based on computations of the atomic charge distribution functions (CDF) in parallel to calculations of the distribution functions of the chemical shifts (SDF) of protons is developed to be applied to a set of complex oxide and carbon nanomaterials. Binary nanooxides (alumina/silica, titania/silica), 3d-metal-doped anatase, activated carbon, carbon nanotube, fullerene C60, graphene oxide, and N-doped Kagome graphene are considered here as representatives of different classes of nanomaterials. The analyses of the CDF and SDF as nonlocal characteristics of certain kinds of atoms in complex systems provide a deeper insight into electronic structure features depending on composition of the materials, guest phase-doped host phase at various amounts of dopants, structure of O- and OH-containing surface sites, amounts and organization of adsorbed water, formation of neutral and charged surface functionalities, bonding of solvated ions, etc. The CDF of metal and hydrogen atoms (electron-donors) are more sensitive to the mentioned factors than the CDF of O, N, and C atoms (electron acceptors) in various systems. As a whole, the use of the CDF and SDF in parallel expands the tool possibility in detailed analysis of the structural and interfacial effects in dried and wetted complex nanomaterials.
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Forni, Alessandra, Elena Cariati, Lucia Carlucci, et al. "Interpreting the different emissive properties of cyclic triimidazole-based CuI and AgI coordination polymers: a QTAIM and IQA study." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 77, no. 6 (2021): 865–70. http://dx.doi.org/10.1107/s2052520621009707.
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A QTAIM and IQA investigation on model compounds of two isostructural AgI and CuI coordination polymers (CPs) based on cyclic triimidazole (L), i.e. the [MIL] n 1D double-stranded stair chain and the [MClL] n 3D network (M = Cu, Ag), has allowed light to be shed on the different emissive behaviour associated with the two metal ions. According to a previously reported investigation [Malpicci et al. (2021). Inorg. Chem. Front. 8, 1312–1323], AgI CPs showed both fluorescence and multiple ligand-centred room-temperature phosphorescences, whereas CuI CPs displayed non-thermally equilibrated halogen and metal-to-ligand charge transfer and two ligand-centred phosphorescences, the latter observed only by their selective activation. Analysis of both local and integral QTAIM descriptors, including delocalization indices and source function, of the Ag—N and Cu—N bonds reveals a higher covalent and local character for the latter, explaining the greater metal–ligand electronic communication observed for the Cu compounds. Moreover, IQA investigation shows that the Cu—N bond is characterized by higher interaction energy, due to both higher electrostatic and exchange-correlation contributions. Analysis on the M—X (M = Ag, Cu; X = I, Cl) bonds, also present in these structures, highlights a much higher covalent and local character with respect to the M—N bonds.
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Daniszewski, Piotr. "Heavy Metals in the Waters of Dąbie Lake (West-Pomeranian Voievodship, North-West Poland)." International Letters of Chemistry, Physics and Astronomy 17 (September 2013): 72–81. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.17.72.
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Heavy metal pollution is an ever increasing problem of our lakes. These toxic heavy metals entering in aquatic environment are adsorbed onto particulate matter, although they can form free metal ions and soluble complexes that are available for uptake by biological organisms. The increase in residue levels of heavy metal content in water, sediments and biota has resulted in decreased productivity and increase in exposure of humans to harmful substances. Many of these metals tend to remain in the ecosystem and eventually move from one compartment to the other within the food chain. Food chain contamination by heavy metals has become a burning issue in recent years because of their potential accumulation in biosystems through contaminated water, soil, sediment and air. Dąbie Lake is an integral part of the River Odra estuary. It is a shallow (2.5 m mean depth) water body with two distinct basins: the large (Dąbie Wielkie) and the small (Dąbie Małe). The aim of the studies, carried out in the years 2008 - 2009, was to determine the content of Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Nickel (Ni), Lead (Pb) and Zinc (Zn) in the waters of Dąbie Lake, being the internal part of the tertiary Odra estuary.
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Daniszewski, Piotr. "Heavy Metals in the Waters of Dąbie Lake (West-Pomeranian Voievodship, North-West Poland)." International Letters of Chemistry, Physics and Astronomy 17 (September 7, 2013): 72–81. http://dx.doi.org/10.56431/p-7ejl06.
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Heavy metal pollution is an ever increasing problem of our lakes. These toxic heavy metals entering in aquatic environment are adsorbed onto particulate matter, although they can form free metal ions and soluble complexes that are available for uptake by biological organisms. The increase in residue levels of heavy metal content in water, sediments and biota has resulted in decreased productivity and increase in exposure of humans to harmful substances. Many of these metals tend to remain in the ecosystem and eventually move from one compartment to the other within the food chain. Food chain contamination by heavy metals has become a burning issue in recent years because of their potential accumulation in biosystems through contaminated water, soil, sediment and air. Dąbie Lake is an integral part of the River Odra estuary. It is a shallow (2.5 m mean depth) water body with two distinct basins: the large (Dąbie Wielkie) and the small (Dąbie Małe). The aim of the studies, carried out in the years 2008 - 2009, was to determine the content of Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Nickel (Ni), Lead (Pb) and Zinc (Zn) in the waters of Dąbie Lake, being the internal part of the tertiary Odra estuary.
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Vlasov, Andrey I., Vladimir P. Zhalnin, Alexander A. Rasuk, and Oleg V. Kosyanov. "Composite Nanomaterials for Implementation of Promising Memristive Structures." Key Engineering Materials 910 (February 15, 2022): 703–12. http://dx.doi.org/10.4028/p-72a77f.
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The paper considers principles of creating promising memristive structures based on composite oxides with agglomerates of nanoparticles. The proposed functional nanomaterial is promising for the formation of a composite structure of a memristor, consisting of two electrodes based on one or more nanoscale layers of metal oxides, which are separated by an active medium so that an insulating layer is applied between the electrodes at the periphery of the active medium region. A conductive layer is formed on top of the insulating layer, which is connected to the negative rail, which prevents leakage of negative oxygen ions through the insulating layer. The authors considered in detail technological process of integral production, which forms the necessary vertical profile of the memristive structure ensuring its greatest stability and repeatability of parameters. The implementation of a hardware-software complex for monitoring and diagnosing a memristive structure is proposed. As a result of the research, an original technical solution was created, which ensures formation of memristive structures with a high efficiency of impact on negative oxygen ions, which are charge carriers in this structure, which ensures their high productivity and stability of parameters.
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Affandi, Trisiani, and Megan M. McEvoy. "Mechanism of metal ion-induced activation of a two-component sensor kinase." Biochemical Journal 476, no. 1 (2019): 115–35. http://dx.doi.org/10.1042/bcj20180577.
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Abstract Two-component systems (TCSs) are essential for bacteria to sense, respond, and adapt to changing environments, such as elevation of Cu(I)/Ag(I) ions in the periplasm. In Escherichia coli, the CusS–CusR TCS up-regulates the cusCFBA genes under increased periplasmic Cu(I)/Ag(I) concentrations to help maintain metal ion homeostasis. The CusS histidine kinase is a homodimeric integral membrane protein that binds to periplasmic Cu(I)/Ag(I) and transduces a signal to its cytoplasmic kinase domain. However, the mechanism of how metal binding in the periplasm activates autophosphorylation in the cytoplasm is unknown. Here, we report that only one of the two metal ion-binding sites in CusS enhances dimerization of the sensor domain. Utilizing nanodisc technology to study full-length CusS, we show that metal-induced dimerization in the sensor domain triggers kinase activity in the cytoplasmic domain. We also investigated autophosphorylation in the cytoplasmic domain of CusS and phosphotransfer between CusS and CusR. In vitro analyses show that CusS autophosphorylates its conserved H271 residue at the N1 position of the histidine imidazole. The phosphoryl group is removed by the response regulator CusR in a reaction that requires a conserved aspartate at position 51. Functional analyses in vivo of CusS and CusR variants with mutations in the autophosphorylation or phosphoacceptor residues suggest that the phosphotransfer event is essential for metal resistance in E. coli. Biochemical analysis shows that the CusS dimer autophosphorylates using a cis mechanism. Our results support a signal transduction model in which rotation and bending movements in the cytoplasmic domain maintain the mode of autophosphorylation.
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Cotty, Stephen Richard, and Xiao Su. "Electrochemical Recovery and Concentration of Noble Metals." ECS Meeting Abstracts MA2022-02, no. 27 (2022): 1042. http://dx.doi.org/10.1149/ma2022-02271042mtgabs.
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Noble metals are integral materials to chemical and electronics industries for their unmatched chemical inertness, electrical conductivity, and catalytic activity. However, the growing demand for noble metals such as Pt, Pd, and Au is outpacing the dwindling supply, and without new recycle strategies these critical noble metal resources will run out. Therefore, energy and resource efficient noble metal recycling technologies are critical to develop sustainable use of these scarce and valuable resources. Recently, electrification of chemical process units has been receiving justifiable attention as an easily scalable means of increasing energy and material sustainability in industry, particularly for chemical separations. In particular, the incorporation of redox-active materials has been met with great success for chemical energy storage and chemical separations due to enhanced charge transfer and easily tunable target ion interactions. Here, we introduce an electrochemically mediated platform for capture, release, and up-concentration of noble metal complexes from mining ore, electronic waste, and valuable elements in industrial manufacturing, where favorable charge transfer binding of noble metals to electrode bound redox sites enables selective capture of target noble metals over other common competitors – all with the flick of a switch. Highlights of our system are its high uptake (>200 mg/g), selectivity (>5 vs competing ions), energy efficiency (<5 kJ/g-PGM), cyclability (>5000 reuse cycles), and scalability to flow system. Technoeconomic analysis of our system compared to current industrial separation technologies indicates economically significant improvements in capital and operating costs with our electrochemical noble metal recycling platform. By lowering the economic barrier of noble metal recycling, these critical materials can be sustainably used and reused for years to come.
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Karami, Zohre, Seyed Mohammad Reza Paran, Poornima Vijayan P., et al. "A Comparative Study on Cure Kinetics of Layered Double Hydroxide (LDH)/Epoxy Nanocomposites." Journal of Composites Science 4, no. 3 (2020): 111. http://dx.doi.org/10.3390/jcs4030111.
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Layered double hydroxide (LDH) minerals are promising candidates for developing polymer nanocomposites and the exchange of intercalating anions and metal ions in the LDH structure considerably affects their ultimate properties. Despite the fact that the synthesis of various kinds of LDHs has been the subject of numerous studies, the cure kinetics of LDH-based thermoset polymer composites has rarely been investigated. Herein, binary and ternary structures, including [Mg0.75 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, [Mg0.75 Al0.25 (OH)2]0.25+ [(NO3−)0.25∙m H2O]0.25− and [Mg0.64 Zn0.11 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, have been incorporated into epoxy to study the cure kinetics of the resulting nanocomposites by differential scanning calorimetry (DSC). Both integral and differential isoconversional methods serve to study the non-isothermal curing reactions of epoxy nanocomposites. The effects of carbonate and nitrate ions as intercalating agents on the cure kinetics are also discussed. The activation energy of cure (Eα) was calculated based on the Friedman and Kissinger–Akahira–Sunose (KAS) methods for epoxy/LDH nanocomposites. The order of autocatalytic reaction (m) for the epoxy/Mg-Al-NO3 (0.30 and 0.254 calculated by the Friedman and KAS methods, respectively) was smaller than that of the neat epoxy, which suggested a shift of the curing mechanism from an autocatalytic to noncatalytic reaction. Moreover, a higher frequency factor for the aforementioned nanocomposite suggests that the incorporation of Mg-Al-NO3 in the epoxy composite improved the curability of the epoxy. The results elucidate that the intercalating anions and the metal constituent of LDH significantly govern the cure kinetics of epoxy by the participation of nitrate anions in the epoxide ring-opening reaction.
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Zaitsev, M. G., V. A. Arlyapov, V. A. Alferov, O. N. Ponamoreva, and A. N. Reshetilov. "A Biosensor for Express Assessment of Integral Toxicity of Polymer- and Textile-Based Products." Biotekhnologiya 37, no. 6 (2021): 119–28. http://dx.doi.org/10.21519/0234-2758-2021-37-6-119-128.
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Biosensors to assess integral toxicity, which consist of an oxygen electrode and immobilized bacteria (Gluconobacter оxydans B-1280 and Escherichia coli К802) or yeast (Saccharomyces cerevisiae Y-1173) have been designed. Model toxic pollutants (phenol, n-nitrophenol, formaldehyde and heavy metal ions Pb2+, Cu2+, Hg2+ and Cr2O72) were chosen to estimate the concentration, at which 50% inhibition of glucose oxidation (ЕC50) was observed. It was shown that a biosensor based on G. оxydans cells provides the most sensitive detection of toxic pollutants, exhibits long operational stability (36 days) and can be used for the detection of integral toxicity. It was shown that the assessment of the toxicity of industrially manufactured polymer- and textile-based products using the developed biosensors and standard test systems (duckweed Lemna minor and protozoa ciliates Stylonychia mytilus) gave similar results. The proposed biosensors can significantly reduce the analysis time compared to the normatively fixed biotesting methods and can be used as a prototype of serial integral toxicity analyzers. biosensor, toxicity, immobilized bacteria Gluconobacter оxydans, Escherichia coli and yeast Saccharomyces cerevisiae, biotesting This research was supported by the State Task of the Ministry of Science and Higher Education of the Russian Federation (no. FEWG-2020-0008).
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ČUPERLOVIĆ-CULF, MIROSLAVA. "THE IMPORTANCE OF INHIBITORS FOR THE SIMULATION OF METABOLIC PROCESSES: IN SILICOZn2+ INHIBITION OF m-ACONITASE FROM ANALYSIS OF GLYCOLYSIS AND KREBS CYCLE KINETIC MODELS." Journal of Bioinformatics and Computational Biology 08, no. 04 (2010): 703–15. http://dx.doi.org/10.1142/s0219720010004872.
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Metal ions have a major effect on the metabolic processes in cells either as inhibitors or as integral components of enzymes. The inhibition of enzymes can take place either through the inhibition of gene expression or through inhibition of protein function. A particularly interesting example of the effect of a metal ion on metabolism is the observed inhibition of Krebs cycle and alteration of energy metabolism by zinc (II) cations. In this particular case metal ion inhibition of enzyme is linked to one of the major functions of prostate cells of accumulation and excretion of citrate. Experimental results have shown that increase in concentration of zinc (II) in prostate cells effectively blocks progression of a part of the Krebs cycle leading to change in the concentration of several metabolites with largest effect in the accumulation of citrate. Based on previously reported experimental results, several distinct mechanisms for zinc (II) inhibition of Krebs cycle were proposed. In order to determine the precise mechanism of inhibition in this system, a mathematical model of glycolysis and Krebs cycle was constructed. Three different types of inhibition were analyzed, including competitive and uncompetitive inhibition as well as inhibition through the alteration of the expression level of m-aconitase. The effects of different inhibition models on metabolite concentrations were investigated as a time course simulation of the system of reactions. Several kinetic parameters in the model were optimized in order to best resemble experimental measurements. The simulation shows that only competitive inhibition leads to an agreement with experimental data.
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Diamant, Viktor, Volodymyr Trachevskii, Katherine Pershina, et al. "Specialties of the structure and conductivity of the non-aqueous electrolytes based on alkali metal bis (salicyl) borates and bis (oxalate) borates." Ukrainian Chemistry Journal 85, no. 3 (2019): 49–55. http://dx.doi.org/10.33609/0041-6045.85.3.2019.49-55.
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The structure and coordination environment of non-aqueous electrolytes based on bis(salicyl)borates of lithium, sodium, potassium, tetramethylammonium (MeBSB) and bis(oxalato)borates from lithium to cesium (MeBOB) using NMR spectroscopy have been investigated. Bis(salicyl)borates (BSB) and bis(oxalate)borates (BOB) of alkali metals and organic cations are considered as promising electroconductive components of electrolytes of modern chemical sources of current (lithium, sodium ion batteries and super-capacitors). The salts were synthesized by the microwave radiation method. The 13C and 11B NMR spectra analysis determined the presence of symmetric structure in BOB anion and the presence of two optical conformations of the BSB anion with labile coordination environment of boron. The conformations of the BSB are the result of the ion contact pairs formation. In the case of tetramethylammonium cation the presence of conformations are depended on the reactive medium. The conformational lability of the coordination sphere of NaBSB dissolved in DMAA is connected with increasing of the integral intensity of carboxyl group singles relatively signals of carbon atoms in fragments of another functional affiliation when the time delay between radio frequencies varies within 2-15 seconds. The difference in the structure of these anions leads to a change in the thermal dependence of the electrical conductivity of BSB and the transport of ions in non-aqueous solvents. Maximum electrical conductivity of salt solutions in DMFA is achieved at close concentrations of 0.75 m for KBSB and 0.77-1 m for NaBSB. The solubility of BSB is better than the BOB. Based on the measurements of the conductivity and the data of electrochemical impedance spectroscopy (the angle of inclination of spectra in the Nyquist coordinates in the low frequency range, the phase angle shift at a frequency) it was proposed the existence of two ways of ions and charge transfer in the electrolytes: diffusion and relay transport. The possibility of formation of a labile salt complex with a solvent due to hydrogen bonds is established.
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Diamant, Viktor, Volodymyr Trachevskii, Katherine Pershina, et al. "Specialties of the structure and conductivity of the non-aqueous electrolytes based on alkali metal bis (salicyl) borates and bis (oxalate) borates." Ukrainian Chemistry Journal 85, no. 3 (2019): 49–55. http://dx.doi.org/10.33609/6045.85.3.2019.49-55.
Full textAbstract:
The structure and coordination environment of non-aqueous electrolytes based on bis(salicyl)borates of lithium, sodium, potassium, tetramethylammonium (MeBSB) and bis(oxalato)borates from lithium to cesium (MeBOB) using NMR spectroscopy have been investigated. Bis(salicyl)borates (BSB) and bis(oxalate)borates (BOB) of alkali metals and organic cations are considered as promising electroconductive components of electrolytes of modern chemical sources of current (lithium, sodium ion batteries and super-capacitors). The salts were synthesized by the microwave radiation method. The 13C and 11B NMR spectra analysis determined the presence of symmetric structure in BOB anion and the presence of two optical conformations of the BSB anion with labile coordination environment of boron. The conformations of the BSB are the result of the ion contact pairs formation. In the case of tetramethylammonium cation the presence of conformations are depended on the reactive medium.
 The conformational lability of the coordination sphere of NaBSB dissolved in DMAA is connected with increasing of the integral intensity of carboxyl group singles relatively signals of carbon atoms in fragments of another functional affiliation when the time delay between radio frequencies varies within 2-15 seconds. The difference in the structure of these anions leads to a change in the thermal dependence of the electrical conductivity of BSB and the transport of ions in non-aqueous solvents. Maximum electrical conductivity of salt solutions in DMFA is achieved at close concentrations of 0.75 m for KBSB and 0.77-1 m for NaBSB. The solubility of BSB is better than the BOB. Based on the measurements of the conductivity and the data of electrochemical impedance spectroscopy (the angle of inclination of spectra in the Nyquist coordinates in the low frequency range, the phase angle shift at a frequency) it was proposed the existence of two ways of ions and charge transfer in the electrolytes: diffusion and relay transport. The possibility of formation of a labile salt complex with a solvent due to hydrogen bonds is established.
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Li, Jinqiu, Yu Duan, Zhaolan Han, et al. "Genome-Wide Identification and Expression Analysis of the NRAMP Family Genes in Tea Plant (Camellia sinensis)." Plants 10, no. 6 (2021): 1055. http://dx.doi.org/10.3390/plants10061055.
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The natural resistant-associated macrophage protein (NRAMP) is a kind of integral membrane transporter which could function on a wide range of divalent metal ions in plants. Little is known about the NRAMP family in Camellia sinensis. In this study, 11 NRAMP genes were identified from the tea plant genome. Phylogenetic analysis showed that the 11 CsNRAMP proteins were split into two groups. The proteins of group 1 contained the conserved motif 6 (GQSSTxTG), while most proteins in group 2 (excepting CsNRAMP7 and CsNRAMP10) contained the conserved residues of motif 6 and motif 2 (GQFIMxGFLxLxxKKW). The number of amino acids in coding regions of 11 CsNRAMP genes ranged from 279–1373, and they contained 3–12 transmembrane domains. Quantitative RT-PCR analysis showed that G1 genes, CsNRAMP3, CsNRAMP4, and CsNRAMP5, were extraordinarily expressed in roots, while G2 genes showed higher expression levels in the stems and leaves. The expression levels of CsNRAMPs in roots and leaves were detected to assess their responses to Pb treatment. The results indicated that CsNRAMPs were differentially regulated, and they might play a role in Pb transportation of tea plant. Subcellular localization assay demonstrated that CsNRAMP2 and CsNRAMP5 fused proteins were localized in the plasma membrane. Overall, this systematic analysis of the CsNRAMP family could provide primary information for further studies on the functional roles of CsNRAMPs in divalent metal transportation in tea plants.
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Natareev, Sergey V., Aleksandr A. Bykov, Dmitriy E. Zakharov, and Tatyana E. Nikiforova. "ION-EXCHANGE IN FLUID-BED DEVICE OF CONTINUOUSLY WORKING." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 2 (2017): 85. http://dx.doi.org/10.6060/tcct.2017602.5372.
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The mathematicaldescription of the process of solution purification from heavy metal ionsby means ofion exchange inan apparatus with continuous suspended layer was developed. At the developing mathematical description the following assumptions were used: the ionite is monodisperse and has a spherical shape, uniform initial distribution of substances in the ionite, the ion exchange equilibrium is described by Henry equation, the velocity of the process is limited by both internal and external diffusion, the ionite in the device moves with longitudinal mixing effect, kinetic and hydrodynamic process parameters are constants. Mathematical description includes the following equations: the diffusion equation of ionite, isotherm equation ion exchange, the equation for average concentration of the substance in the ionite, equations of the one-parameter diffusion model, initial and boundary conditions. To solve boundary value problem, we use the integral Laplace transformmations. The obtained equation allows calculating the solution concentration at the output of the apparatus. The authors determined the validity of the mathematical model on the example of the water purification from zinc ions on the KU-2-8 cationite in the continuous single-chamber apparatus with a fluidized bed. The ion exchange unit has a cylindrical body with a diameter of 0.08 m and a conical bottom. Distributive lattice with thickness of 3×10-3 m and with holes with diameter of 2×10-3 m and orifice of 20.6 % were located in the lower part of the device. The height of the fluid-bed ionite layer in the device was 0.12 m. The chamber for separation of ion exchanger and solution was placed in the top of the device. This chamber had a cylindrical shape with a diameter of 0.15 m and height of 0.1 m. The chamber for fluid-bed ionite and chamber for separation of ionite and solution were joined conical shell. The solution flow rate in the apparatus was 2.1×10-5 m3/s. The ionite flow rate in the device was 1.42×10-7 m3/s. The initial concentration of the solution of zinc chloride was taken 5.1×10-3 kg-eq/ m3. The concentration of zinc ions in the spent ionite was 0.67 kg-eq/m3. The concentration of zinc ions in the purified solution was 6.4×10-4 kg-eq/m3. The calculated value of concentration of zinc ions in the spent ionite was 0.66 kg-eq/m3. The calculated value of concentration of zinc ions in the purified solution was 7.2×10-4 kg-eq/m3. The deviation of the calculated results from the experimental data does not exceed 12 %. The elaborated mathematical model is recommended for practical application. For citation:Natareev S.V., BykovА.А., Zakharov D.E., Nikiforova T.E. Ion-exchange in fluid-bed device of continuously working. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N2. P. 85-90.
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Zeng, Xing, Tong Gao, Linhui Xie, and Zijian He. "Analytical Solution of the One-Dimensional Transport of Ionic Contaminants in Porous Media with Time-Varying Velocity." Water 15, no. 8 (2023): 1530. http://dx.doi.org/10.3390/w15081530.
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The one-dimensional convection–dispersion equation has been widely used to describe the migration process of contaminant leachate through barriers. However, most of the existing solutions are limited to simple conditions. In this study, a one-dimensional convection–dispersion model with time-dependent velocity was established while considering the change in the permeability coefficient. The analytical solution of the model was obtained by using the integral transformation method. Based on the analytical model, three special conditions were assumed for comparison. The results showed that the concentration levels of pollutants inside the barrier would significantly increase with the increase in the flow velocity, and the pollutant concentrations inside the barrier would be increased by four times compared with the normal flow velocity when the flow rate increased by two times. The transports of heavy metal ions with variable velocities through soil–bentonite and soil–attapulgite barriers were predicted under field conditions. The predicted results showed that the breakthrough time would be reduced by as much as two times. In engineering practice, a barrier’s service performance can be improved by controlling the temperature of the seepage field and improving the chemical compatibility of the barrier materials.
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Bryant, Sheenah, Tyler Clark, Christopher Thomas, et al. "Insights into the Voltage Regulation Mechanism of the Pore-Forming Toxin Lysenin." Toxins 10, no. 8 (2018): 334. http://dx.doi.org/10.3390/toxins10080334.
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Lysenin, a pore forming toxin (PFT) extracted from Eisenia fetida, inserts voltage-regulated channels into artificial lipid membranes containing sphingomyelin. The voltage-induced gating leads to a strong static hysteresis in conductance, which endows lysenin with molecular memory capabilities. To explain this history-dependent behavior, we hypothesized a gating mechanism that implies the movement of a voltage domain sensor from an aqueous environment into the hydrophobic core of the membrane under the influence of an external electric field. In this work, we employed electrophysiology approaches to investigate the effects of ionic screening elicited by metal cations on the voltage-induced gating and hysteresis in conductance of lysenin channels exposed to oscillatory voltage stimuli. Our experimental data show that screening of the voltage sensor domain strongly affects the voltage regulation only during inactivation (channel closing). In contrast, channel reactivation (reopening) presents a more stable, almost invariant voltage dependency. Additionally, in the presence of anionic Adenosine 5′-triphosphate (ATP), which binds at a different site in the channel’s structure and occludes the conducting pathway, both inactivation and reactivation pathways are significantly affected. Therefore, the movement of the voltage domain sensor into a physically different environment that precludes electrostatically bound ions may be an integral part of the gating mechanism.
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Marcus, Yizhak. "Preferential Solvation of Ions in Mixed Solvents. 5. The Alkali Metal, Silver, and Thallium(I) Cations in Aqueous Organic Solvents According to the Inverse Kirkwood-Buff Integral (IKBI) Approach." Journal of Solution Chemistry 36, no. 11-12 (2007): 1385–99. http://dx.doi.org/10.1007/s10953-007-9196-4.
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Jin, Lan. "Genome-Wide Identification and Expression Analysis of the NRAMP Family in Melon." International Journal of Agriculture and Biology 25, no. 02 (2021): 332–37. http://dx.doi.org/10.17957/ijab/15.1672.
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The NRAMPs (natural resistance-associated macrophage proteins) are evolutionarily conserved integral membrane proteins that transport a broad range of metal ions. A comprehensive analysis of NRAMP family genes has not been reported for melon (Cucumis melo). In this study, six CmNRAMP genes were identified from the melon genome. Analyses of gene structure, phylogeny, chromosome location and conserved motifs revealed two groups of CmNRAMPs: one group contained only CmNRAMP5, which had 12 conserved motifs like NRAMPs in Arabidopsis thaliana and rice (Oryza sativa). The other group contained five CmNRAMPs and all had shorter amino acid sequences compared with CmNRAMP5. Expression analyses suggested that CmNRAMP genes are expressed differently in response to treatments with different plant hormones, abiotic factors, and metals (iron, copper, and manganese). The most responsive gene was CmNRAMP5, which showed significant changes in its transcript levels in response to abscisic acid (ABA), indole acetic acid, cytokinin, methyl jasmonate, brassinosteroid, Fe, and Cu. The least responsive gene was CmNARMP6, which was only significantly responsive to ABA, Fe, and Mn. These results indicate that CmNRAMP genes function in numerous tissues and at different developmental stages. A protein–protein interaction analysis indicated that CmNRAMPs interact with proteins involved in transmembrane transport, superoxide dismutase activity, plant hormone signal transduction, signal transduction by protein phosphorylation, and nicotianamine synthase activity. This study provides valuable insights into the potential function of CmNRAMP genes and their encoded products. © 2021 Friends Science Publishers
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Chik, Nur Syazwanie Izzati, Norin Zamiah Binti Kassim Shaari, Nur Azrini Binti Ramlee, and Muhamad Rezza Bin Abdul Manaf. "Extraction of Silica from Rice Husk Ash and Its Effect on the Properties of the Integral Membrane." ASM Science Journal 17 (November 17, 2022): 1–13. http://dx.doi.org/10.32802/asmscj.2022.1035.
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The large generation of agricultural residue could pose an environmental issue that lies through the disposal problem. Therefore, the incorporation of rice husk ash (RHA) into the membrane formulation could curb this problem besides adding value to the biomass. Rice husk ash is widely used as a filler for a polymer composite to enhance its mechanical properties due to the presence of silica. This research incorporated RHA into the membrane formulation. The silica in the RHA was extracted using an acid-leaching process and dried into silica powder. The silica powder was characterised by using an X-Ray diffractometer (XRD) and X-Ray fluorescence (XRF). A sol-gel method with hydrochloric acid as the catalyst was used in the fabrication of polysulfone/chitosan/polyvinyl alcohol membrane, and the extracted silica powder was incorporated in the formulations. The membranes were characterised in terms of functional groups using Fourier Transform Infrared Spectroscopy (FTIR), surface morphology using Scanning Electron Emission (SEM) analysis, and surface hydrophilicity using contact angle analysis. Finally, the performance of the membrane was analysed by pure water flux and antifouling. The XRD and XRF results showed that the extracted silica powder contained 77% of silica with the absence of impurities. The cross-linking reaction of membranes occurred as the Si–O–C bond was detected at 1,105cm−1 after the FTIR analysis, and a compact structure of the membrane was detected from the SEM analysis. The results from pure water flux portrayed that the membranes incorporated with silica (M1 and M2) had better integral stability compared to that from the pure polymer, which was observed from the consistent value of flux throughout the 1-hour filtration time and no swelling of the membranes after the performance testing. The results also showed that the extraction of silica from the RHA using a modified process was successfully conducted, and the silica powder was also compatible with the membrane solution as no separate layer was formed. Thus, the produced membranes have the potential to be used in the treatment of wastewater containing heavy metal ions.
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ROUHI, A. MAUREEN. "Escorting Metal Ions." Chemical & Engineering News 75, no. 45 (1997): 34–35. http://dx.doi.org/10.1021/cen-v075n045.p034.
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Spillmann, C., D. Osorio, and R. Waugh. "Integrin Activation by Divalent Ions Affects Neutrophil Homotypic Adhesion." Annals of Biomedical Engineering 30, no. 8 (2002): 1002–11. http://dx.doi.org/10.1114/1.1511241.
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DAVISON, I., G. SHANKAR, M. A. HORTON, and W. T. MASON. "Integrin-dependent Mobilization of Intracellular Calcium Ions in Osteoclasts." Annals of the New York Academy of Sciences 710, no. 1 Toxins and Ex (1994): 287–300. http://dx.doi.org/10.1111/j.1749-6632.1994.tb26636.x.
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Bella, Jordi, and Helen M. Berman. "Integrin–collagen complex: a metal–glutamate handshake." Structure 8, no. 6 (2000): R121—R126. http://dx.doi.org/10.1016/s0969-2126(00)00153-2.
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Griffin, David H., Guther Winkelmann, and Dennis R. Winge. "Metal Ions in Fungi." Mycologia 87, no. 3 (1995): 425. http://dx.doi.org/10.2307/3760843.
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Schweikhard, L., St Becker, K. Dasgupta, et al. "Trapped metal cluster ions." Physica Scripta T59 (January 1, 1995): 236–43. http://dx.doi.org/10.1088/0031-8949/1995/t59/032.
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Ragan, C. Ian. "Metal Ions in Neuroscience." Metal-Based Drugs 4, no. 3 (1997): 125–32. http://dx.doi.org/10.1155/mbd.1997.125.
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Metal ions are believed to participate in many neurodegenerative conditions. In excitotoxic cell death there is convincing evidence for the participation of Ca2+ and Zn2+ ions although the exact molecular mechanisms by which these metals exert their effects are unclear. Only in one instance has the metal binding site of metalloenzymes been exploited for therapeutic purposes and this is the use of Li+ in the treatment of bipolar affective disorder. Again the exact molecular target is not clear but is likely to involve a Mg2+-dependent enzyme of an intracellular signalling pathway. In Parkinson's disease, the selective loss of dopaminergic neurones in the substantia nigra may be caused by radical-mediated damage and there is good evidence to suggest that Fe2+ or 3+ is important in promoting formation of radical species. The evidence that free radicals are important in mediating other neurodegenerative conditions is less strong but still substantial enough to suggest that removal of reactive oxygen species or preventing their formation may be a valid approach to therapy.
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Crabtree, R. H. "Metal Ions at Work." Science 266, no. 5190 (1994): 1591–92. http://dx.doi.org/10.1126/science.266.5190.1591.
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Navasivayam, C. "Biosorbents for metal ions." Bioresource Technology 64, no. 2 (1998): 161. http://dx.doi.org/10.1016/s0960-8524(98)00014-5.
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Blake, Diane A., Robert C. Blake II, Mehraban Khosraviani, and Andrey R. Pavlov. "Immunoassays for metal ions." Analytica Chimica Acta 376, no. 1 (1998): 13–19. http://dx.doi.org/10.1016/s0003-2670(98)00437-1.
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