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Yong Yao, Samit Kumar Dutta, Sang Ho Park, Ratan Rai, L Miya Fujimoto, Andrey A Bobkov, Stanley J Opella, Francesca M Marassi
The outer membrane protein Ail (Adhesion invasion locus) is one of the most abundant proteins on the cell surface of Yersinia pestis during human infection. Its functions are expressed through interactions with a variety of human host proteins, and are essential for microbial virulence. Structures of Ail have been determined by X-ray diffraction and solution NMR spectroscopy, but those samples contained detergents that interfere with functionality, thus, precluding analysis of the structural basis for Ail's biological activity...
February 26, 2017: Journal of Biomolecular NMR
Anthony R Braun, Michael M Lacy, Vanessa C Ducas, Elizabeth Rhoades, Jonathan N Sachs
α-Synuclein is the primary protein found in Lewy bodies, the protein and lipid aggregates associated with Parkinson's disease and Lewy body dementia. The protein folds into a uniquely long amphipathic α-helix (AH) when bound to a membrane, and at high enough concentrations, it induces large-scale remodeling of membranes (tubulation and vesiculation). By engineering a less hydrophobic variant of α-Synuclein, we previously showed that the energy associated with binding of α-Synuclein's AH correlates with the extent of membrane remodeling (Braun et al...
February 26, 2017: Journal of Membrane Biology
Y Manolova, H Marciniak, S Tschierlei, F Fennel, F S Kamounah, S Lochbrunner, L Antonov
The solvent dependent excited state dynamics of 4-hydroxy-3-(piperidin-1-ylmethyl)-1-naphthaldehyde (compound 2), a candidate for a molecular switch based on intramolecular proton transfer, was investigated by ultrafast spectroscopy and quantum-chemical calculations. In acetonitrile a mixture of molecules in the enol and zwitterionic proton transfer (PT) form exists in the ground state. However, the zwitterion is the energetically favored one in the electronically excited state. Optical excitation of the enol form results in intramolecular proton transfer and formation of the PT form within 1...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
P S Gaikar, S T Navale, S L Gaikwad, Ahmed Al-Osta, V V Jadhav, P R Arjunwadkar, Mu Naushad, Rajaram S Mane
In the present study, beta-cobalt hydroxide (β-Co(OH)2) electrodes of various nanostructures and surface areas, viz. nano-rhombuses (NRs), nano-plates (NPs), and nano-grass (NGs), have been synthesized directly onto a stainless-steel (SS) substrate using a simple, economical and binder-free chemical solution-process, utilizing three cobalt precursor salts, i.e. cobalt acetate, cobalt chloride, and cobalt nitrate, respectively. Structural elucidation proves the crystallite size, type and phase-purity of β-Co(OH)2, whereas the surface morphology analysis supports the evolution of the above mentioned nanostructures of various surface areas...
February 27, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Junjie Li, Deqiang Yin, Qiang Li, Rong Sun, Sumei Huang, Fanzhi Meng
Unravelling the atomic structure and chemical species of interfacial defects is critical to understanding the origin of interfacial properties in many heterojunctions. Here, by combining advanced transmission electron microscopy, spectroscopy and first-principles calculations, we demonstrate interfacial Ti diffusion in SrVO3/SrTiO3 and LaCrO3/SrTiO3 heterointerfaces and uncover that the interfacial defects induce a significant change in electronic properties by showing an electronic transformation from the insulating state to metallic state at SrVO3/SrTiO3 heterointerfaces due to the hybridization of interfacial Ti d, O p and V d, and a metallic to insulating state transformation at LaCrO3/SrTiO3 because of Ti-Cr mixing induced charge redistribution in the interfacial layer...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Matthew J DiTucci, Fabian Böhm, Gerhard Schwaab, Evan R Williams, Martina Havenith
The valency of aqueous solutes plays a large role in determining the extent of ion-water dynamics, which can greatly influence the chemical and physical properties of solutions. In these experiments, broadband Fourier transform terahertz spectroscopy is used to probe perturbations to the low-frequency dynamics of water molecules by three different multivalent hexacyanoferrate salts. K3Fe(CN)6, K4Fe(CN)6 and Na4Fe(CN)6 were investigated as a function of concentration up to their solubility limits using spectral subtractions and fitting with damped harmonic lineshapes...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
M Tchaplyguine, M-H Mikkelä, E Mårsell, C Polley, A Mikkelsen, W Zhang, A Yartsev, C J D Hetherington, L R Wallenberg, O Björneholm
Organic-shell-free PbS nanoparticles have been produced in the size range relevant for quantum-dot solar cells (QDSCs) by a vapor aggregation method involving magnetron reactive sputtering. This method creates a beam of free 5-10 nm particles in a vacuum. The dimensions of the particles were estimated after their deposition on a substrate by imaging them using ex situ SEM and HRTEM electron microscopy. The particle structure and chemical composition could be deduced "on the fly", prior to deposition, using X-ray photoelectron spectroscopy (XPS) with tunable synchrotron radiation...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Ievgen Kurylo, Mathieu Dupré, Sonia Cantel, Christine Enjalbal, Hervé Drobecq, Sabine Szunerits, Oleg Melnyk, Rabah Boukherroub, Yannick Coffinier
In this paper, we report an original method to immobilize a model peptide on silicon nanowires (SiNWs) via a photolinker attached to the SiNWs' surface. The silicon nanowires were fabricated by a metal assisted chemical etching (MACE) method. Then, direct characterization of the peptide immobilization on SiNWs was performed either by X-ray photoelectron spectroscopy (XPS) or by laser-desorption/ionization mass spectrometry (LDI-MS). XPS allowed us to follow the peptide immobilization and its photorelease by recording the variation of the signal intensities of the different elements present on the SiNW surface...
February 27, 2017: Analyst
Janice J Hwang, Lihong Jiang, Muhammad Hamza, Feng Dai, Renata Belfort-DeAguiar, Gary Cline, Douglas L Rothman, Graeme Mason, Robert S Sherwin
Fructose has been implicated in the pathogenesis of obesity and type 2 diabetes. In contrast to glucose, CNS delivery of fructose in rodents promotes feeding behavior. However, because circulating plasma fructose levels are exceedingly low, it remains unclear to what extent fructose crosses the blood-brain barrier to exert CNS effects. To determine whether fructose can be endogenously generated from glucose via the polyol pathway (glucose → sorbitol → fructose) in human brain, 8 healthy subjects (4 women/4 men; age, 28...
February 23, 2017: JCI Insight
Khadijeh Shekoohi, Fatemeh Sadat Hosseini, Amir Hossein Haghighi, Atefe Sahrayian
Hydrotalcites are quite prevalent in nature and their importance is growing more and more because of their very wide range of potential applications and uses. Because hydrotalcite does not exist in significant quantities in nature, coprecipitation methods are the most used for prepartion of hydrotalcite. In this study: Two types of Nano hydrotalcite compounds containing one divalent (Mg-Al) and two divalent cation(Co-Mg-Al) were synthesized based on aqueous solutions of corresponding nitrates by co-precipitation method...
2017: MethodsX
Fathima S Ameer, Shilpa Varahagiri, Donald W Benza, Daniel R Willett, Yimei Wen, Fenglin Wang, George Chumanov, Jeffrey N Anker
We describe a simple technique to alter the shape of silver nanoparticles (AgNPs) by rolling a glass tube over them to mechanically compress them. The resulting shape change in turn induces a red-shift in the localized surface plasmon resonance (LSPR) scattering spectrum and exposes new surface area. The flattened particles were characterized by optical and electron microscopy, single nanoparticle scattering spectroscopy, and surface enhanced Raman spectroscopy (SERS). AFM and SEM images show that the AgNPs deform into discs; increasing the applied load from 0 to 100 N increases the AgNP diameter and decreases the height...
September 22, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Kai F Kalz, Ralph Kraehnert, Muslim Dvoyashkin, Roland Dittmeyer, Roger Gläser, Ulrike Krewer, Karsten Reuter, Jan-Dierk Grunwaldt
In the future, (electro-)chemical catalysts will have to be more tolerant towards a varying supply of energy and raw materials. This is mainly due to the fluctuating nature of renewable energies. For example, power-to-chemical processes require a shift from steady-state operation towards operation under dynamic reaction conditions. This brings along a number of demands for the design of both catalysts and reactors, because it is well-known that the structure of catalysts is very dynamic. However, in-depth studies of catalysts and catalytic reactors under such transient conditions have only started recently...
January 9, 2017: ChemCatChem
Wei-Ji Wang, Zheng-Song Qiu, Han-Yi Zhong, Wei-An Huang, Wen-Hao Dai
Emulsifier-free poly(methyl methacrylate-styrene) [P(MMA-St)] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcohol-water medium by a solvothermal method. Then, through radical graft copolymerization of thermo-sensitive monomer N-isopropylacrylamide (NIPAm) and hydrophilic monomer acrylic acid (AA) onto the surface of P(MMA-St) nanospheres at 80 °C, a series of thermo-sensitive polymer nanospheres, named SD-SEAL with different lower critical solution temperatures (LCST), were prepared by adjusting the mole ratio of NIPAm to AA...
2017: Pet Sci
Suhui Ye, Brian Molloy, Alfredo F Braña, Daniel Zabala, Carlos Olano, Jesús Cortés, Francisco Morís, José A Salas, Carmen Méndez
Genome mining of the mithramycin producer Streptomyces argillaceus ATCC 12956 revealed 31 gene clusters for the biosynthesis of secondary metabolites, and allowed to predict the encoded products for 11 of these clusters. Cluster 18 (renamed cluster arp) corresponded to a type I polyketide gene cluster related to the previously described coelimycin P1 and streptazone gene clusters. The arp cluster consists of fourteen genes, including genes coding for putative regulatory proteins (a SARP-like transcriptional activator and a TetR-like transcriptional repressor), genes coding for structural proteins (three PKSs, one aminotransferase, two dehydrogenases, two cyclases, one imine reductase, a type II thioesterase, and a flavin reductase), and one gene coding for a hypothetical protein...
2017: Frontiers in Microbiology
Alice J Sweeting, François Billaut, Matthew C Varley, Ramón F Rodriguez, William G Hopkins, Robert J Aughey
Purpose: To quantify the effect of acute hypoxia on muscle oxygenation and power during simulated team-sport running. Methods: Seven individuals performed repeated and single sprint efforts, embedded in a simulated team-sport running protocol, on a non-motorized treadmill in normoxia (sea-level), and acute normobaric hypoxia (simulated altitudes of 2,000 and 3,000 m). Mean and peak power was quantified during all sprints and repeated sprints. Mean total work, heart rate, blood oxygen saturation, and quadriceps muscle deoxyhaemoglobin concentration (assessed via near-infrared spectroscopy) were measured over the entire protocol...
2017: Frontiers in Physiology
Z Aziz, B C Bostick, Y Zheng, M R Huq, M M Rahman, K M Ahmed, A van Geen
Reductive dissolution of iron oxyhydroxides and reduction of arsenic are often invoked as leading causes of high dissolved As levels in shallow groundwater of Bangladesh. The second of these assumptions is questioned here by comparing the behavior As and phosphate (P), a structural analogue for As (V) which also adsorbs strongly to Fe oxyhydroxides but is not subject to reduction. The first line of evidence is provided by a detailed groundwater time-series spanning two years for three wells in the 6-9 m depth range showing removal of As(III) from shallow groundwater during the monsoon without of loss of P...
February 2017: Applied Geochemistry: Journal of the International Association of Geochemistry and Cosmochemistry
Harry B Gray, Jay R Winkler
Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O2-reactive enzymes, raising the possibility that they play an antioxidant protective role...
October 2016: Israel Journal of Chemistry
Gyungsu Jin, Jeongeun Kim, Yunhee Lee, Jinyeong Kim, Casimir C Akoh, Hyang Sook Chun, Sangdoo Ahn, Byung Hee Kim
The aim of this study was to discriminate the geographic origin of Korean, Chinese, and Indian sesame oils distributed in Korea using (1)H NMR spectroscopy in combination with canonical discriminant analysis (CDA). (1)H NMR spectra were obtained from 84 roasted oil samples prepared from 51 Korean, 19 Chinese, and 14 Indian sesame seeds. The integration values of 26 peaks observed in the NMR spectra were determined and normalized on the basis of the peak derived from the terminal CH3 of the fatty acids (0.7446-1...
February 24, 2017: Journal of Oleo Science
Chen-Ming Lee, Paul E Luner, Karen Locke, Katherine Briggs
The objective of this study was to develop an artificial stomach-duodenum (ASD) dissolution model as an in vitro evaluation tool that would simulate the gastrointestinal physiology of gastric pH-reduced dogs as a method to assess formulations for a poorly soluble free acid compound with ng/mL solubility. After establishing the ASD model with well controlled duodenum pH, five formulations each applying different solubilization principles were developed and their performance in the ASD model and in vivo in dogs was evaluated...
February 23, 2017: Journal of Pharmaceutical Sciences
Nagore Andraka, Lissete Sánchez-Magraner, Marcos García-Pacios, Félix M Goñi, José L R Arrondo
Human phospholipid scramblase 1 (SCR) is a membrane protein that catalyzes the transmembrane (flip-flop) motion of phospholipids. It can also exist in a non membrane-bound form in the nucleus, where it modulates several aspects of gene expression. Catalysis of phospholipid flip-flop requires the presence of millimolar Ca(2+), and occurs in the absence of ATP. Membrane-bound SCR contains a C-terminal α-helical domain embedded in the membrane bilayer. The latter domain can be removed giving rise to a stable truncated mutant SCRΔ that is devoid of scramblase activity...
February 23, 2017: Biochimica et Biophysica Acta
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