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https://www.readbyqxmd.com/read/29161496/ion-transport-across-biological-membranes-by-carborane-capped-gold-nanoparticles
#1
Marcin P Grzelczak, Stephen P Danks, Robert C Klip, Domagoj Belic, Adnana Zaulet, Casper Kunstmann-Olsen, Dan F Bradley, Tatsuya Tsukuda, Clara Viñas, Francesc Teixidor, Jonathan J Abramson, Mathias Brust
2-3 nm carborane-capped gold nanoparticles (Au/carborane NPs) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst-Equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning...
November 21, 2017: ACS Nano
https://www.readbyqxmd.com/read/29161051/a-new-avenue-for-limiting-degradation-in-nanoli4ti5o12-for-ultra-fast-charge-lithium-ion-batteries-hybrid-polymer-inorganic-particles
#2
Jean-Christophe Daigle, Yuichiro Asakawa, Mélanie Beaupré, René Vieillette, Dharminder Laul, Michel L Trudeau, Karim Zaghib
Lithium titanium oxide (Li4Ti5O12)-based cells are a very promising battery technology for ultra-fast charge-discharge and long-life cycle batteries. However, surface reactivity of lithium titanium oxide is still a problem in presence of organic electrolyte which may cause expansion of the pouch cell. In this study, we report on the development of a simple and economical ''grafting onto'' method for forming hybrid polymer-Li4Ti15O12 nanoparticles which can be successfully applied in lithium-ion batteries. This method utilizes a low-cost and scalable hydrophobic polymer which is required for industrial implantation...
November 21, 2017: Nano Letters
https://www.readbyqxmd.com/read/29160933/xyloglucan-in-the-primary-cell-wall-assessment-by-fesem-selective-enzyme-digestions-and-nanogold-affinity-tags
#3
Yunzhen Zheng, Xuan Wang, Yuning Chen, Edward Wagner, Daniel J Cosgrove
Xyloglucan has been hypothesized to bind extensively to cellulose microfibril surfaces and to tether microfibrils into a load-bearing network, thereby playing a central role in wall mechanics and growth, but this view is challenged by newer results. Here we combined high-resolution imaging by Field-Emission Scanning Electron Microscopy (FESEM) with nanogold affinity tags and selective endoglucanase treatments to assess the spatial location and conformation of xyloglucan in onion cell walls. FESEM imaging of xyloglucanase-digested cell walls revealed an altered microfibril organization but did not yield clear evidence of xyloglucan conformations...
November 21, 2017: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/29160899/persistent-sample-circulation-microextraction-combined-with-graphite-furnace-atomic-absorption-spectroscopy-for-trace-determination-of-heavy-metals-in-fish-species-marketed-in-kermanshah-iran-and-human-health-risk-assessment
#4
Yahya Safari, Mostafa Karimaei, Kiomars Sharafi, Hossein Arfaeinia, Masoud Moradi, Nazir Fattahi
BACKGROUND: The persistent sample circulation microextraction (PSCME) joined with the graphite furnace atomic absorption spectrometry (GFAAS) was developed as a high preconcentration technique for the determination of heavy metals in fish species. In this method, a few microliter of organic solvent (40.0 µl carbon tetrachloride) was transferred to the bottom of a conical sample cup. Then a 10.0 ml of aqueous solution transformed to fine droplets while passing through an organic solvent...
November 21, 2017: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/29160871/molecular-mechanism-of-activation-of-burkholderia-cepacia-lipase-at-aqueous-organic-interfaces
#5
Ivan Pires de Oliveira, Gabriel Ernesto Jara, Leandro Martínez
Lipases are water-soluble enzymes that catalyze the hydrolysis of lipids. Since lipids are mostly hydrophobic, lipase activity occurs preferentially at interfaces of aqueous and organic phases. In this work, we study the molecular mechanisms by which the Burkholderia cepacia lipase (BCL) is activated at interfaces of water with octane and with methyl caprylate (CAME). We show that BCL assumes very rapidly a preferential orientation at the interfaces, in which the active site is exposed to the organic phase...
November 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29160710/evaporation-dynamics-of-mixed-nanocolloidal-sessile-droplets
#6
Binita Pathak, Sandeep Hatte, Saptarshi Basu
Evaporation dynamics of a particle laden droplet has been a topic of interest in recent times due to its widespread applications, ranging from surface patterning to drug delivery systems. The interplay of evaporation induced internal flow dynamics, contact line dynamics and nanoparticle self-assembly govern the morphologies of the residual structures. Fine tuning of these residual structures is thus possible by controlling the governing parameters. A nanoparticle laden sessile droplet placed on a hydrophobic substrate undergoes buckling phenomenon which results in a dome-like structure with cavity on the surface...
November 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29160602/mitochondrial-ribosome-bl34-mutants-present-diminished-translation-of-cytochrome-c-oxidase-subunits
#7
Raquel Fonseca Guedes-Monteiro, José Ribamar Ferreira-Junior, Lucas Bleicher, Francisco G Nóbrega, Antoni Barrientos, Mario H Barros
Saccharomyces cerevisiae mitoribosomes are specialized in the translation of a few number of highly hydrophobic membrane proteins, components of the oxidative phosphorylation system. Mitochondrial characteristics, such as the membrane system and its redox state driven mitoribosomes evolution through great diversion from their bacterial and cytosolic counterparts. Therefore, mitoribosome presents a considerable number of mitochondrial-specific proteins, as well as new protein extensions. In this work we characterize temperature sensitive mutants of the subunit bL34 present in the 54S large subunit...
November 21, 2017: Cell Biology International
https://www.readbyqxmd.com/read/29160329/effects-of-length-and-hydrophilicity-hydrophobicity-of-diamines-on-self-assembly-of-diamine-sds-gemini-like-surfactants
#8
Zhidi Chen, Jeffrey Penfold, Peixun Li, James Doutch, Yaxun Fan, Yilin Wang
This work studied gemini-like surfactants formed from anionic surfactant sodium dodecyl sulfate (SDS) and cationic charged bola-type diamines with hydrophilic or hydrophobic spacers of different lengths using surface tension, small angle neutron scattering, isothermal titration microcalorimetry and cryogenic transmission electron microscopy. The critical micelle concentrations (CMC) and the surface tension at CMC (γCMC) for all the diamine/SDS mixtures are markedly lower than that of SDS. The shorter diamines reduce γCMC to a greater extent regardless of the hydrophilicity/hydrophobicity of the diamines...
November 21, 2017: Soft Matter
https://www.readbyqxmd.com/read/29160078/formation-of-lipid-bilayer-nanodiscs-by-diisobutylene-maleic-acid-dibma-copolymer
#9
Abraham Olusegun Oluwole, Johannes Klingler, Bartholomäus Danielczak, Jonathan Oyebamiji Babalola, Carolyn Vargas, Georg Pabst, Sandro Keller
Membrane proteins usually need to be extracted from their native environment and separated from other membrane components for in-depth in vitro characterization. The use of styrene/maleic acid (SMA) copolymers to solubilize membrane proteins and their surrounding lipids into bilayer nanodiscs is an attractive approach toward this goal. We have recently shown that diisobutylene/maleic acid (DIBMA) copolymer similarly solubilizes model and cellular membranes but, unlike SMA(3:1), has a mild impact on lipid acyl-chain order and thermotropic phase behavior...
November 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29159976/design-and-study-of-lipopeptide-inhibitors-on-preventing-aggregation-of-human-islet-amyloid-polypeptide-residues-11-20
#10
Yexuan Mao, Lanlan Yu, Mengfan Mao, Chuanguo Ma, Lingbo Qu
Type 2 diabetes mellitus, a kind of conformational disease, has become an epidemic disease, which seriously endangers the quality of life and health of human beings. The deposition of human islet amyloid polypeptide (hIAPP) has been considered as one of the major pathological features of type 2 diabetes mellitus. As lipopeptides have some hydrophobic groups, which are similar to the reported aggregation inhibitors, and some lipopeptides could prevent cells from depositing of amyloid fibrils, several potential lipopeptide inhibitors have been engineered and synthesized, which have been assessed for their inhibitory effect in preventing amyloid fibrils formation of hIAPP11-20 by using the conventional thioflavin-T fluorescence assay and new technique microscale thermophoresis (MST)...
November 21, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/29159445/probiotic-properties-and-cellular-antioxidant-activity-of-lactobacillus-plantarum-ma2-isolated-from-tibetan-kefir-grains
#11
Wei Tang, Chao Li, Zengguo He, Fen Pan, Shuo Pan, Yanping Wang
Lactobacillus plantarum MA2 was isolated from traditional Chinese Tibetan kefir grains. Its antioxidant properties had been demonstrated in vitro and in vivo previously. In the present study, the probiotic characteristics of this strain were further evaluated by investigating its acid and bile salt tolerances, cell surface hydrophobicity, and autoaggregation, respectively. In addition, the cellular antioxidant activity (CAA) assay was applied to test the antioxidant capacity of the isolate in different growth phases...
November 20, 2017: Probiotics and Antimicrobial Proteins
https://www.readbyqxmd.com/read/29159350/mucopenetrating-micelles-with-a-peg-corona
#12
Essi M Taipaleenmäki, Sidsel A Mouritzen, Philipp S Schattling, Yan Zhang, Brigitte Städler
Crossing the intestinal mucus layer is a long-standing challenge for orally delivered nanoparticles carrying therapeutic cargo. We report the assembly of mucopenetrating cargo-loaded micelles using block copolymers consisting of either linear poly(ethylene glycol) (PEG) or bottle-brush poly(oligo(ethylene glycol)methacrylate) (PEGb) as the hydrophilic block and poly(caprolactone) (PCL) or poly(cholesteryl methacrylate) (PCMA) as the hydrophobic extension. The micelles were shown to preserve their stability and retain ∼50% of their cargo in simulated gastric fluid...
November 21, 2017: Nanoscale
https://www.readbyqxmd.com/read/29159346/peramivir-analogues-bearing-hydrophilic-side-chains-exhibit-higher-activities-against-h275y-mutant-than-wild-type-influenza-virus
#13
Din-Chi Chiu, Tzu-Chen Lin, Wen-I Huang, Ting-Jen Cheng, Keng-Chang Tsai, Jim-Min Fang
Peramivir is an effective anti-influenza drug in the clinical treatment of influenza, but its efficacy toward the H275Y mutant is reduced. The previously reported cocrystal structures of inhibitors in the mutant neuraminidase (NA) suggest that the hydrophobic side chain should be at the origin of reduced binding affinity. In contrast, zanamivir having a hydrophilic glycerol side chain still possesses high affinity toward the H275Y NA. We thus designed five peramivir analogues (5-9) carrying hydrophilic glycol or glycerol side chains, and evaluated their roles in anti-influenza activity, especially for the H275Y mutant...
November 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29159142/investigation-of-the-binding-mechanism-and-inhibition-of-bovine-liver-catalase-by-quercetin-multi-spectroscopic-and-computational-study
#14
Samaneh Rashtbari, Gholamreza Dehghan, Reza Yekta, Abolghasem Jouyban
Introduction: The study on the side effects of various drugs and compounds on enzymes is a main issue for monitoring the conformational and functional changes of them. Quercetin (3,5,7,3',4'-pentahydroxyflavone, QUE), a polyphenolic flavonoid, widely found in fruits, vegetables and it is used as an ingredient in foods and beverages. The interaction of bovine liver catalase (BLC) with QUE has been studied in this research by using different spectroscopic methods. Methods: In this work, the interaction of QUE with BLC was investigated using different spectroscopic methods including ultraviolet-visible (UV-vis) absorption, circular dichroism (CD) and fluorescence spectroscopy and molecular docking studies...
2017: BioImpacts: BI
https://www.readbyqxmd.com/read/29158816/dual-targeting-theranostic-system-with-mimicking-apoptosis-to-promote-myocardial-infarction-repair-via-modulation-of-macrophages
#15
Jingli Chen, Jun Yang, Ruiyuan Liu, Chenmeng Qiao, Zhiguo Lu, Yuanjie Shi, Zhanming Fan, Zhenzhong Zhang, Xin Zhang
Currently unsatisfactory treatment of myocardial infarction (MI) is due to the unbridled inflammation and the delayed diagnosis at the early stage. To address these problems, firstly, phosphatidylserine (PS) was used to modulate the phenotypes of macrophages (MΦ) and resolve the early inflammation via binding to PS receptors (PSR) on macrophage surface. Secondly, highly-sensitive magnetic iron oxide nanocubes (MIONs) were adopted to realize the early visualization via magnetic resonance imaging (MRI). However, the major drawback for MIONs as contrast agents was their hydrophobic properties and insufficient delivery...
2017: Theranostics
https://www.readbyqxmd.com/read/29158409/hydrophobicity-of-proteins-and-nanostructured-solutes-is-governed-by-topographical-and-chemical-context
#16
Erte Xi, Vasudevan Venkateshwaran, Lijuan Li, Nicholas Rego, Amish J Patel, Shekhar Garde
Hydrophobic interactions drive many important biomolecular self-assembly phenomena. However, characterizing hydrophobicity at the nanoscale has remained a challenge due to its nontrivial dependence on the chemistry and topography of biomolecular surfaces. Here we use molecular simulations coupled with enhanced sampling methods to systematically displace water molecules from the hydration shells of nanostructured solutes and calculate the free energetics of interfacial water density fluctuations, which quantify the extent of solute-water adhesion, and therefore solute hydrophobicity...
November 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29158386/cholesterol-binding-site-of-the-influenza-m2-protein-in-lipid-bilayers-from-solid-state-nmr
#17
Matthew R Elkins, Jonathan K Williams, Martin D Gelenter, Peng Dai, Byungsu Kwon, Ivan V Sergeyev, Bradley L Pentelute, Mei Hong
The influenza M2 protein not only forms a proton channel but also mediates membrane scission in a cholesterol-dependent manner to cause virus budding and release. The atomic interaction of cholesterol with M2, as with most eukaryotic membrane proteins, has long been elusive. We have now determined the cholesterol-binding site of the M2 protein in phospholipid bilayers using solid-state NMR spectroscopy. Chain-fluorinated cholesterol was used to measure cholesterol proximity to M2 while sterol-deuterated cholesterol was used to measure bound-cholesterol orientation in lipid bilayers...
November 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29158337/a-single-residue-mutation-in-the-g%C3%AE-q%C3%A2-subunit-of-the-g-protein-complex-causes-blindness-in-drosophila
#18
Jinguo Cao, Murali K Bollepalli, Yuhui Hu, Jin Zhang, Qiang Li, Hongmei Li, Hua Chang, Feng Xiao, Roger C Hardie, Yikang S Rong, Wen Hu
Heterotrimeric G proteins play central roles in many signaling pathways, including the phototransduction cascade in animals. However, the degree of involvement of the G protein subunit Gαq is not clear since animals with strong loss of function mutations previously reported remain responsive to light stimuli. We recovered a new allele of Gαq in Drosophila that abolishes light response in a conventional ERG assay, and reduces sensitivity in whole-cell recordings of dissociated cells by at least 5 orders of magnitude...
November 20, 2017: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/29158275/a-simplified-derivative-of-human-defensin-5-with-potent-efficiency-against-multidrug-resistant-acinetobacter-baumannii
#19
Cheng Wang, Gaomei Zhao, Song Wang, Yin Chen, Yali Gong, Shilei Chen, Yang Xu, Mengjia Hu, Xinmiao Wang, Hao Zeng, Aiping Wang, Dengqun Liu, Yongping Su, Tianmin Cheng, Fang Chen, Junping Wang
The increasing incidence of multidrug-resistant Acinetobacter baumannii (MDRAb) infections worldwide has necessitated the development of novel antibiotics. Human defensin 5 (HD5) is an endogenous peptide with a complex architecture and antibacterial activity against MDRAb In the present study, we attempted to simplify the structure of HD5 by removing disulfide bonds. We found that the Cys2-4 bond was most indispensable for HD5 to inactivate MDRAb, although the antibacterial activity of the derivative was significantly attenuated...
November 20, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/29157902/interaction-of-catecholamine-precursor-l-dopa-with-lysozyme-a-biophysical-insight
#20
Saima Nusrat, Aiman Masroor, Masihuz Zaman, Mohd Khursheed Siddiqi, Mohammad Rehan Ajmal, Nida Zaidi, Ali Saber Abdelhameed, Rizwan Hasan Khan
The current study comprises of an inclusive biophysical study, enlightening the binding of L-3, 4-dihydroxyphenylalanine (L-Dopa) with human lysozyme (HL) and hen egg white lysozyme (HEWL). Spectroscopic and molecular docking tools have been utilized to study the interaction of L-Dopa with both HL and HEWL. Spectrofluorimetric measurements exhibited that L-Dopa quenched the HL and HEWL intrinsic fluorescence. A binding constant (Kb) of ∼10(4)M(-1) for both HL and HEWL was obtained, asserting a significant binding...
November 17, 2017: International Journal of Biological Macromolecules
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