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electrostatic ligand

Thanuja Gangi Setty, Jonathan C Mowers, Aaron G Hobbs, Shubha P Maiya, Sanaa Syed, Robert S Munson, Michael A Apicella, Ramaswamy Subramanian
The primary role of bacterial periplasmic binding proteins is sequestration of essential metabolites present at a low concentration in the periplasm and making them available for active transporters that transfer these ligands into the bacterial cell. The periplasmic binding proteins(SiaP) from the tripartite ATP-independent periplasmic (TRAP) transport system that transports mammalian host-derived sialic acids, have been well studied from different pathogenic bacteria, including Haemophilus influenzae , Fusobacterium nucleatum , Pasteurella multocida , and Vibrio cholerae SiaPs bind the sialic acid N-acetylneuraminic acid (Neu5Ac) with nanomolar affinity by forming electrostatic and hydrogen bonding interactions...
October 12, 2018: Journal of Biological Chemistry
Andy K M Lam, Raimund Dutzler
TMEM16A is a ligand-gated anion channel that is activated by intracellular Ca2+ . This channel contains two independent pores and closely apposed Ca2+ binding sites that are contained within each subunit of a homodimeric protein. Previously we characterized the influence of positively charged pore-lining residues on anion conduction (Paulino C. et. al., 2017). Here, we demonstrate the electrostatic control of permeation by the bound calcium ions in mouse TMEM16A using electrophysiology and Poisson-Boltzmann calculations...
October 12, 2018: ELife
William A Golding, Robert Pearce-Higgins, Robert J Phipps
Control of site-selectivity in chemical reactions that occur remote from existing functionality remains a major challenge in synthetic chemistry. We describe a strategy that enables three of the most commonly used cross-coupling processes to occur with high site-selectivity on dichloroarenes which bear acidic functional groups. We have achieved this by repurposing an established sulfonylated phosphine ligand to exploit its inherent bifunctionality. Mechanistic studies suggest that the sulfonate group engages in attractive electrostatic interactions with the associated cation of deprotonated substrate, guiding cross-coupling to the chloride at the arene meta-position...
October 8, 2018: Journal of the American Chemical Society
Lin Ma, Mengyue Zhang, Aijun Yang, Qin Wang, Fei Qu, Fengli Qu, Rong-Mei Kong
Heparin (Hep) is widely used as a major anticoagulant in surgery. Simple and sensitive methods capable of quantitative detection of Hep are desired for better regulating its clinical use. Herein, a novel nanoassembly of amino-functionalized mesoporous silica nanoparticle-gold nanoclusters (MSN-AuNCs) with remarkable emission enhancement characteristics for sensitive fluorescence detection of Hep is developed. The electrostatic interaction between the positively charged amino-functionalized MSNs and the AuNC-stabilizing surface ligands triggers the self-assembly of MSN-AuNC nanocomposites which exhibit more than 5-fold fluorescence emission enhancement...
October 8, 2018: Analyst
Ani Wang, Ruiqing Fan, Xinxin Pi, Yuze Zhou, Guangyu Chen, Wei Chen, Yulin Yang
Heteroatom-doped porous carbons are emerging as platforms for gas adsorption. Herein, N-doped microporous carbon (NPCs) materials have been synthesized by carbonization of two pyridine-ligand based Metal-Organic Complexes (MOCs) at high temperatures (800, 900, 1000 and 1100 °C). For the NPCs (termed NPC-1-T and NPC-2-T, T represents the carbonization temperature), micropore is dominant, pyridinic-N and other N atom of MOC precursors mostly retained, the N content reaches as high as 16.61 %. They all show high BET surface area and pore volume, in particular, NPC-1-900 exhibits the highest surface areas and pore volumes, up to 1656...
October 8, 2018: ACS Applied Materials & Interfaces
Enora Prado, Laureen Bonnat, Hugues Bonnet, Thomas Lavergne, Angeline Van Der Heyden, Genevieve Pratviel, Jerome Dejeu, Eric Defrancq
Surface plasmon resonance (SPR) is a powerful technique to study the interactions of ligands with analytes and therefore a number of biosensor surfaces and injection methods have been developed so far. However, many experimental parameters can affect the interactions and consequently the affinity measurements. In particular the interactions of positively charged analytes (often used for anionic nucleic acids targets) can be influenced by the sensing surfaces (e.g. negatively charged) leading to significant non-specific interactions as well as regeneration problems...
October 7, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Alexander Wilkinson, Eric Lattmann, Carla B Roces, Gabriel Pedersen, Dennis Christensen, Yvonne Perrie
Pattern recognition receptors, including the Toll-like receptors (TLRs), are important in the induction and activation of two critical arms of the host defence to pathogens and microorganisms; the rapid innate immune response (as characterised by the production of Th1 promoting cytokines and type 1 interferons) and the adaptive immune response. Through this activation, ligands and agonists of TLRs can enhance immunotherapeutic efficacy. Resiquimod is a small (water-soluble) agonist of the endosome-located Toll-like receptors 7 and 8 (TLR7/8)...
October 3, 2018: Journal of Controlled Release: Official Journal of the Controlled Release Society
Chiranjib Gogoi, Shyam Biswas
A Zr(iv) based luminescent metal-organic framework (MOF; 1) was synthesized by a solvothermal method using a mixture of ZrCl4, quinoline-2,6-dicarboxylic acid (H2QDA) ligand and trifluoroacetic acid (modulator) having a 1 : 1 : 10 molar ratio in N,N-dimethylformamide (DMF). For activation, the methanol-exchanged sample was heated under high vacuum at 120 °C for 1 day. Different techniques like X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy and energy dispersive X-ray (EDX) analysis were applied to fully characterize 1...
October 3, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Siti Nurulnabila A Rahaman, Jastina Mat Yusop, Zeti-Azura Mohamed-Hussein, Wan Mohd Aizat, Kok Lian Ho, Aik-Hong Teh, Jitka Waterman, Boon Keat Tan, Hwei Ling Tan, Adelicia Yongling Li, Ee Sin Chen, Chyan Leong Ng
Proteins of the DUF866 superfamily are exclusively found in eukaryotic cells. A member of the DUF866 superfamily, C1ORF123, is a human protein found in the open reading frame 123 of chromosome 1. The physiological role of C1ORF123 is yet to be determined. The only available protein structure of the DUF866 family shares just 26% sequence similarity and does not contain a zinc binding motif. Here, we present the crystal structure of the recombinant human C1ORF123 protein (rC1ORF123). The structure has a 2-fold internal symmetry dividing the monomeric protein into two mirrored halves that comprise of distinct electrostatic potential...
2018: PeerJ
Cynthia M Hong, Robert G Bergman, Kenneth N Raymond, F Dean Toste
The field of supramolecular chemistry has its foundation in molecular recognition and selective binding of guest molecules, often with remarkably strong binding affinities. The field evolved to leverage these favorable interactions between the host and its guest to catalyze simple, often biomimetic transformations. Drawing inspiration from these early studies, self-assembled supramolecular hosts continue to capture a significant amount of interest toward their development as catalysts for increasingly complex transformations...
October 1, 2018: Accounts of Chemical Research
Yukinobu Kodama, Ryo Noda, Kayoko Sato, Hitomi Harasawa, Tomoaki Kurosaki, Hiroo Nakagawa, Tadahiro Nakamura, Takashi Kitahara, Takahiro Muro, Hitoshi Sasaki
Folate receptors are overexpressed on the surface cancer cells. We successfully constructed a new gene delivery vector of methotrexate (MTX)-coated plasmid DNA-polyethylenimine (pDNA-PEI) complexes (PEI complexes) by electrostatic binding. The stable anionic nanoparticle was optimized at MTX charge ratios of 120 or more. pDNA-PEI-MTX complexes (MTX complexes) demonstrated gene expression efficiency as high as cationic pDNA-PEI complexes in the mouse melanoma cell line, B16-F10. The MTX complexes were taken up by the cell-specific uptake mechanisms via the folate receptor...
2018: Biological & Pharmaceutical Bulletin
Jianxin Liu, Kairui Feng, Yujie Ren
Maladjustment of the Wnt signalling pathway can lead to a variety of cancers. Axin can be expressed stably through the Tankyrases (TNKS) inhibitor, thus inducing the degradation of β-catenin, antagonizing the Wnt signalling pathway and consequently inhibiting tumour growth. Thus, TNKS has become a hot research target for anticancer drugs, and a systematic study of tetrazoloquinoxaline analogues as TNKS inhibitors is of considerable value. In this paper, 3D-QSAR, molecular docking and DISCOtech were applied to study a series of tetrazoloquinoxaline and establish good CoMFA (q2 =0...
September 27, 2018: Journal of Biomolecular Structure & Dynamics
Ria Biswas, Nilkanta Chowdhury, Ranjita Mukherjee, Angshuman Bagchi
The interaction of the proteins, tumor necrosis factor receptor-associated factor6 (TRAF6) and Basigin (CD147), is known to be associated with the over-expression of matrix metalloproteinases (MMPs) in melanoma cells. MMPs are known to be responsible for melanoma metastasis. Hence, the TRAF6-Basigin complex can act as a potential therapeutic target. In previous studies, amino acid residues Lys340, Lys 384, Glu417 and Glu511 of TRAF6 were identified as the most vital residues on the basis of their contributions to interaction energy, relative solvent accessibility and electrostatic interactions in the TRAF6-Basigin protein-protein interaction (PPI) scheme...
September 17, 2018: Journal of Molecular Graphics & Modelling
Lijie Shi
Protein kinase C (PKC) is a family of signal transducing enzymes that have been implicated in anesthetic preconditioning signaling cascade. Evidences are emerging that certain exogenous neuromodulators such as n-alkanols and general anesthetics can stimulate PKC activity by binding to regulatory C1A domain of the enzyme. However, the accurate binding sites in C1A domain as well as the molecular mechanism underlying binding-stimulated PKC activation still remain unelucidated. Here, we report a systematic investigation of the intermolecular interaction of human PKCδ C1A domain with its natural activator phorbol ester (PE) and co-activator dioleoylglycerol (DOG) as well as exogenous stimulators butanol, octanol and sevoflurane...
September 24, 2018: Protein Journal
Ganesan Kumaravel, Ponya Utthra Ponnukalai, Dharmasivam Mahendiran, Natarajan Raman
This work deals with a series of biologically important novel transition metal(II) Schiff base chelates containing terpyridine. Benzimidazole, a moiety found in broad spectrum of drugs is espoused in a Schiff base ligand system. Eight such metal(II) complexes are designed, synthesized and characterized. An octahedral geometry has been envisaged for all the complexes. DNA-binding behaviours are studied by absorption titration, electrochemical, viscosity, fluorescence and circular dichroism methods. The DNA cleavage ability is also evaluated by agarose gel electrophoresis method...
September 20, 2018: International Journal of Biological Macromolecules
Haotian Hao, Guifeng Liu, Yili Wang, Baoyou Shi, Kun Han, Yuan Zhuang, Yan Kong
In this study, a regenerable magnetic core-shell nanoparticles NH2 -Fe3 O4 -NTA which include 3-aminopropyltriethoxysilane (APTES) and nitrilotriacetic acid (NTA) crosslinked to Fe3 O4 was developed by one-pot method for simultaneous removal of cationic and anionic metals. Another nanocomposite NH2 -Fe3 O4 -NTAII was prepared by multi-step method for comparison. NH2 -Fe3 O4 -NTA had positive zeta potential values of 35.1-0.8 mV at pH 1.8-11.0, with the saturation magnetization and surface area up to 40.56 emu/g and 56...
September 1, 2018: Journal of Hazardous Materials
Hezron Timothy Mwakabona, Hilda R Mlay, Bart Van der Bruggen, Karoli N Njau
Defluoridation properties of two Fe(III)-loaded plant biomass (Fe(III)-activated sisal fibre (Fe(III)-ASF) and post-alkalized Fe(III)-ASF (PA-Fe(III)-ASF)) distinguished by preparation pathways through exclusion/inclusion of post-alkalization are presented, with the aim of understanding the influence of post-alkalization in the preparation pathway to their fluoride removal properties. Findings reveal that PA-Fe(III)-ASF shows higher chemical stability with removal efficiency increasing towards acidic conditions, whereas Fe(III)-ASF manifests a lower chemical stability with removal efficiency increasing (in a wider pH range) with the increase in pH...
September 9, 2018: Journal of Hazardous Materials
Jinjian Wei, Hideyuki Mitomo, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Masayuki Naya, Kuniharu Ijiro
The self-assembly of gold nanoparticles (GNPs) into a defined structure, particularly hollow capsule structures, provides great potential for applications in materials science and medicine. However, the complexity of the parameters for the preparation of those structures through self-assembly has limited access to critical mechanistic questions. With this in mind, we have studied GNP vesicle (GNV) formation through self-assembly by the surface modification of GNPs with low-molecular-weight ligands. Here, we successfully prepared GNVs composed of GNPs with a diameter of 30 nm by surface modification with carboxylic acid-terminated fluorinated oligo(ethylene glycol) ligands (CFLs)...
October 1, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Jin Zhang, Christin Grundström, Kristoffer Brännström, Irina Iakovleva, Mikael Lindberg, Anders Olofsson, Patrik L Andersson, A Elisabeth Sauer-Eriksson
Thyroid-disrupting chemicals (TDCs) are xenobiotics that can interfere with the endocrine system and cause adverse effects in organisms and their offspring. TDCs affect both the thyroid gland and regulatory enzymes associated with thyroid hormone homeostasis. Transthyretin (TTR) is found in the serum and cerebrospinal fluid of vertebrates, where it transports thyroid hormones. Here, we explored the interspecies variation in TDC binding to human and fish TTR (exemplified by Gilthead seabream ( Sparus aurata))...
October 2, 2018: Environmental Science & Technology
Pramod Jagtap, Rituraj Mishra, Shruti Khanna, Pratibha Kumari, Bhanu Mittal, Hemant K Kashyap, Shalini Gupta
The increasing problem of multidrug resistance (MDR) in bacteria calls for discovery of new molecules and diagnostic methodologies that are effective against a wide range of microbial pathogens. We have studied the role of alexidine dihydrochloride (alex) as a bioaffinity ligand against lipopolysaccharide (LPS), a pathogen-associated surface marker universally present on all Gram-negative bacteria. While the activity of alex against bacteria is biologically known, little information exists on its mechanism of action or binding stoichiometry...
September 18, 2018: ACS Infectious Diseases
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