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https://www.readbyqxmd.com/read/29457729/assessing-interactions-between-a-polytopic-membrane-protein-and-lipid-bilayers-using-differential-scanning-calorimetry-and-solid-state-nmr
#1
James R Banigan, Maureen Leninger, Ampon Sae Her, Nathaniel J Traaseth
It is known that the lipid composition within a cellular membrane can influence membrane protein structure and function. In this Article, we investigated how structural changes to a membrane protein upon substrate binding can impact the lipid bilayer. To carry out this study, we reconstituted the secondary active drug transporter EmrE into a variety of phospholipid bilayers varying in headgroup and chain length and carried out differential scanning calorimetry (DSC) and solid-state NMR experiments. The DSC results revealed a difference in cooperativity of the lipid phase transition for drug-free EmrE protonated at glutamic acid 14 (i...
February 19, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29457713/probing-structural-changes-among-analogous-inhibitor-bound-forms-of-hiv-1-protease-and-a-drug-resistant-mutant-in-solution-by-nuclear-magnetic-resonance
#2
Shahid N Khan, John D Persons, Janet L Paulsen, Michel Guerrero, Celia A Schiffer, Nese Kurt-Yilmaz, Rieko Ishima
In the era of state-of-the-art inhibitor design and high-resolution structural studies, detection of significant but small protein structural differences in the inhibitor-bound forms is critical to further developing the inhibitor. Here, we probed differences in HIV-1 protease (PR) conformation among darunavir and four analogous inhibitor-bound forms and compared them with a drug-resistant mutant using nuclear magnetic resonance chemical shifts. Changes in amide chemical shifts of wild-type (WT) PR among these inhibitor-bound forms, ΔCSP, were subtle but detectable and extended >10 Å from the inhibitor-binding site, asymmetrically between the two subunits of PR...
February 19, 2018: Biochemistry
https://www.readbyqxmd.com/read/29457687/substrate-binding-drives-active-site-closing-of-human-blood-group-b-galactosyltransferase-as-revealed-by-hot-spot-labeling-and-nmr-experiments
#3
Thomas Peters, Sophie Weissbach, Friedemann Flügge
Crystallography has shown that human blood group A (GTA) and B (GTB) glycosyltransferases undergo transitions between "open", "semi-closed", and "closed" conformations upon substrate binding. However, the time scales of corresponding conformational reorientations are unknown. Crystal structures show that Trp and Met residues are located at "conformational hot spots" of the enzymes. Therefore, we have utilized 15N-side chain labeling of Trp residues, and 13C-methyl labeling of Met residues to study substrate induced conformational transitions of GTB...
February 19, 2018: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/29457352/controllable-bipolar-doping-of-graphene-with-2d-molecular-dopants
#4
Boseok Kang, Haena Kim, Joong Tark Han, Dae Gun Kim, Kilwon Cho
The fine control of graphene doping levels over a wide energy range remains a challenging issue for the electronic applications of graphene. Here, the controllable doping of chemical vapor deposited graphene, which provides a wide range of energy levels (shifts up to ± 0.5 eV), is demonstrated through physical contact with chemically versatile graphene oxide (GO) sheets, a 2D dopant that can be solution-processed. GO sheets are a p-type dopant due to their abundance of electron-withdrawing functional groups...
February 19, 2018: Small
https://www.readbyqxmd.com/read/29455982/investigation-of-oh-bond-energy-for-chemically-treated-alfa-fibers
#5
Arwa Turki, Asma El Oudiani, Slah Msahli, Faouzi Sakli
This work aims to study the hydrogen bond energy and distance for different samples of alfa fibers treated with thymol. The treatment duration and thymol concentration were varied and seem to have a great influence on infrared band intensities and positions. The number of hydrogen bonds is related to the infrared band intensity, whereas their energy and distance depend on the infrared band position. It was proven that the free hydroxyl groups are weakened and tend to disappear with fiber treatment. It is the same for intermolecular hydrogen bands between cellulosic chains that present a decrease in both intensity and frequency...
April 15, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29455077/raman-studies-of-the-interactions-of-fibrous-carbon-nanomaterials-with-albumin
#6
Aleksandra Wesełucha-Birczyńska, Krzysztof Morajka, Ewa Stodolak-Zych, Elżbieta Długoń, Maria Dużyja, Tomasz Lis, Maciej Gubernat, Magdalena Ziąbka, Marta Błażewicz
Adsorption or immobilization of proteins on synthetic surfaces is a key issue in the context of the biocompatibility of implant materials, especially those intended for the needs of cardiac surgery but also for the construction of biosensors or nanomaterials used as drug carriers. The subject of research was the analysis of Raman spectra of two types of fibrous carbon nanomaterials, of great potential for biomedical applications, incubated with human serum albumin (HSA). The first nanomaterial has been created on the layer of MWCNTs deposited by electrophoretic method (EPD) and then covered by thin film of pyrolytic carbon introduced by chemical vapor deposition process (CVD)...
February 7, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29454872/simultaneous-formation-of-3-deoxy-d-threo-hexo-2-ulose-and-3-deoxy-d-erythro-hexo-2-ulose-during-the-degradation-of-d-glucose-derived-amadori-rearrangement-products-mechanistic-considerations
#7
Martin Kaufmann, Sophie Krüger, Clemens Mügge, Lothar W Kroh
Analyzing classical model reaction systems of Amadori rearrangement products (ARP) it became apparent that the formation of 3-deoxy-d-threo-hexo-2-ulose (3-deoxygalactosone, 3-DGal) during the degradation of ARPs is highly dependent on pH and the amino acid residue of the respective ARP. Based on a detailed analysis of the NMR chemical shifts of the sugar moieties of different ARPs, it could be derived that the formation of 3-DGal is sensitive to the stability of a co-operative hydrogen bond network which involves HO-C3, the deprotonated carboxyl functionality and the protonated amino nitrogen of the amino acid substituent...
February 12, 2018: Carbohydrate Research
https://www.readbyqxmd.com/read/29453758/theoretical-study-on-the-optical-response-behavior-to-hydrogen-chloride-gas-of-a-series-of-schiff-base-based-star-shaped-structures
#8
Fei Wang, Tianhong Qi, Zhongmin Su, Yuzhong Xie
Schiff-base compounds have many applications in the field of optoelectronic materials and chemical sensing because of their appealing coordination ability, and simple and easily accessible use in structural modification. Herein, five kinds of star-shaped Schiff-base compounds were designed and their optical response behavior to hydrogen chloride (HCl) gas was studied using dependent/time-dependent density functional theory (DFT/TDDFT). Moreover, the relationship between structures and properties was investigated upon changing the benzene group into N atom or triazine group at the core-position and introducing a methoxyl (-OCH 3 ) or nitro (-NO 2 ) group into the star-shaped Schiff-bases at the tail of the branches...
February 17, 2018: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/29451129/stress-evolution-of-ge-nanocrystals-in-dielectric-matrices
#9
Rahim Bahariqushchi, Rosario Raciti, Ahmet Emre Kasapoğlu, Emre Gür, Meltem Sezen, Eren Kalay, Salvatore Salvatore Mirabella, Atilla Aydınlı
Germanium nanocrystals (Ge NCs) embedded in single and multilayer silicon oxide and silicon nitride matrices have been synthesized using plasma enhanced chemical vapor deposition (PECVD) followed by conventional furnace annealing (CFA) or rapid thermal processing (RTP) in N2 ambient. Compositions of the films were determined by Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS). Formation of nanocrystals under suitable process conditions were observed with high resolution transmission electron microscope (HRTEM) micrographs and Raman spectroscopy...
February 16, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29450824/solid-state-13-c-15-n-nmr-resonance-assignment-of-hepatitis-b-virus-core-protein
#10
Lauriane Lecoq, Shishan Wang, Thomas Wiegand, Stéphane Bressanelli, Michael Nassal, Beat H Meier, Anja Böckmann
Each year, nearly 900,000 deaths are due to serious liver diseases caused by chronic hepatitis B virus infection. The viral particle is composed of an outer envelope and an inner icosahedral nucleocapsid formed by multiple dimers of a ~ 20 kDa self-assembling core protein (Cp). Here we report the solid-state 13 C and 15 N resonance assignments of the assembly domain, Cp149, of the core protein in its capsid form. A secondary chemical shift analysis of the 140 visible residues suggests an overall alpha-helical three-dimensional fold matching that derived for Cp149 from the X-ray crystallography of the capsid, and from solution-state NMR of the Cp149 dimer...
February 16, 2018: Biomolecular NMR Assignments
https://www.readbyqxmd.com/read/29449940/effects-of-fumaric-acid-supplementation-on-methane-production-and-rumen-fermentation-in-goats-fed-diets-varying-in-forage-and-concentrate-particle-size
#11
Zongjun Li, Nannan Liu, Yangchun Cao, Chunjia Jin, Fei Li, Chuanjiang Cai, Junhu Yao
Background: In rumen fermentation, fumaric acid (FA) could competitively utilize hydrogen with methanogenesis to enhance propionate production and suppress methane emission, but both effects were diet-dependent. This study aimed to explore the effects of FA supplementation on methanogenesis and rumen fermentation in goats fed diets varying in forage and concentrate particle size. Methods: Four rumen-cannulated goats were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments: low or high ratio of forage particle size: concentrate particle size (Fps:Cps), without or with FA supplementation (24 g/d)...
2018: Journal of Animal Science and Biotechnology
https://www.readbyqxmd.com/read/29449087/two-dimensional-correlation-spectroscopic-studies-on-coordination-between-organic-ligands-and-ni-2-ions
#12
Ya-Nan Bao, Yi-Wei Zeng, Ran Guo, Mesude Ablikim, Hai-Fang Shi, Li-Min Yang, Zhan-Lan Yang, Yi-Zhuang Xu, Isao Noda, Jin-Guang Wu
3 A 2g → 3 T 1g (P) transition band of Ni 2+ is used to probe the coordination of Ni 2+ . Two-dimensional asynchronous spectra (2DCOS) are generated using the Double Asynchronous Orthogonal Sample Design (DAOSD), Asynchronous Spectrum with Auxiliary Peaks (ASAP) and Two-Trace Two-Dimensional (2T2D) approaches. Cross peaks relevant to the 3 A 2g → 3 T 1g (P) transition band of Ni 2+ are utilized to probe coordination between Ni 2+ and various ligands. We studied the spectral behavior of the 3 A 2g → 3 T 1g (P) transition band when Ni 2+ is coordinated with ethylenediaminetetraacetic acid disodium salt (EDTA)...
December 7, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29448706/visible-light-photocatalytic-performance-of-in-situ-synthesized-graphite-sio%C3%A2-tio%C3%A2-composite-towards-degradation-of-benzene-gas
#13
Hemraj Mahipati Yadav, Sang-Chul Jung, Jung-Sik Kim
Graphite-SiO2-TiO2 composites with optimum graphite and SiO2 loadings were prepared by a facile one-pot chemical route. The structural, morphological and physiochemical properties of the samples were investigated by analytical techniques. UV-Vis-DRS analysis confirmed light absorbance edge of composites was sharply red-shifted to the visible region with increasing graphite and SiO2 content. The prepared composites showed higher photocatalytic activity towards degradation of benzene gas under visible light. The contribution of graphite and SiO2 on the enchantment of visible light photocatalytic performance of the composites was discussed...
March 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29448700/uv-photoluminescence-of-alumino-germano-silicate-glass-optical-fiber-incorporated-with-gd%C3%A2-o%C3%A2-nano-particles-upon-illumination-of-xenon-lamp
#14
Seongmin Ju, Kadathala Linganna, Bok Hyeon Kim, Seongjae Boo, Yong Ho An, Won-Taek Han
Alumino-germano-silicate glass optical fiber incorporated with Gd2O3 nano-particles (NPs) was developed by using the modified chemical vapor deposition and the drawing process. The formation of spherical Gd2O3 NPs in the fiber core with average diameter of 10.8 nm was confirmed by the TEM. The distinct absorption peaks in the fiber preform appearing in the UV region at 205, 247, 253, 274, and 312 nm were due to the incorporated Gd2O3 NPs via reorganization of the seven 4f electrons into various multiplets of Gd ions...
March 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29448233/earth-s-field-nmr-detection-of-oil-under-arctic-ice-water-suppression
#15
Mark S Conradi, Stephen A Altobelli, Nicholas J Sowko, Susan H Conradi, Eiichi Fukushima
Earth's field NMR has been developed to detect oil trapped under or in Arctic sea-ice. A large challenge, addressed here, is the suppression of the water signal that dominates the oil signal. Selective suppression of water is based on relaxation time T 1 because of the negligible chemical shifts in the weak earth's magnetic field, making all proton signals overlap spectroscopically. The first approach is inversion-null recovery, modified for use with pre-polarization. The requirements for efficient inversion over a wide range of B 1 and subsequent adiabatic reorientation of the magnetization to align with the static field are stressed...
February 7, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29448227/alignment-of-nematic-liquid-crystals-decorated-with-gemini-surfactants-and-interaction-of-proteins-with-gemini-surfactants-at-fluid-interfaces
#16
Tongtong Tian, Qi Kang, Tao Wang, Jianhong Xiao, Li Yu
A series of cationic gemini surfactants with diverse chemical structures, that is, imidazolium-based gemini surface active ionic liquids (gemini IM-SAILs) with different alkyl chain length or spacer length, viz. 1,s-bis(3-alkylimidazolium-1-yl) ethane bromide ([C n -s-C n im]Br 2 ; s = 2, n = 6, 8, 10, 12, 16; n = 12, s = 2, 4, 6, 10), and quaternary ammonium-based gemini surfactants (gemini QASaa) with different symmetries, viz. 1,2-bisalkylquaternary ammonium bromide (m-2-n; m = 12, 14, 16, n = 8, 10, 12, m + n = 24), were synthesized and utilized to decorate aqueous/liquid crystal interfaces (ALI)...
February 9, 2018: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29446945/a-statistical-model-to-decipher-protein-folding-unfolding-at-a-local-scale
#17
Paul Grassein, Patrice Delarue, Harold Abraham Scheraga, Gia G Maisuradze, Patrick Senet
Protein folding/unfolding can be analysed experimentally at a local scale by monitoring the physical properties of local probes as a function of the temperature, as for example the distance between fluorophores or the values of chemical shifts of backbone atoms. Here, the analytical Lifson-Roig model for the helix-coil transition is modified to analyse local thermal unfolding of the fast-folder W protein of bacteriophage lambda (gpW) simulated by all-atom molecular dynamics (MD) simulations in explicit solvent at fifteen different temperatures...
February 15, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29446612/total-capture-convection-limited-nanofluidic-immunoassays-exhibiting-nanoconfinement-effects
#18
Casey J Galvin, Kentaro Shirai, Ali Rahmani, Kakuta Masaya, Amy Q Shen
Understanding nanoconfinement phenomena is necessary to develop nanofluidic technology platforms. One example of nanoconfinement phenomena are shifts in reaction equilibria toward reaction products in nanoconfined systems, which have been predicted theoretically and observed experimentally in DNA hybridization. Here we demonstrate a convection limited nanofluidic immunoassay that achieves total capture of a target analyte, and an apparent shift in the antibody-antigen reaction equilibrium due to nanoconfinement...
February 15, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29443502/direct-classification-of-gc-%C3%A3-gc-analyzed-complex-mixtures-using-non-negative-matrix-factorization-based-feature-extraction
#19
Yasuyuki Zushi, Shunji Hashimoto
Complex chemical mixtures need to be evaluated to, for example, aid in medical diagnoses, assess product quality, and assess environmental conditions. Two-dimensional gas chromatography (GC × GC), which is a comprehensive analytical technique, combined with data classification techniques has attracted great interest for assessing mixtures. In this study, a nontarget cross-sample analysis-based unsupervised direct classification method using non-negative matrix factorization was developed for assessing mixtures analyzed by GC × GC...
February 14, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29442664/synthesis-of-au-ag-alloy-nanoparticles-in-deionized-water-by-pulsed-laser-ablation-technique
#20
W Norsyuhada, W M Shukri, Noriah Bidin, Shumaila Islam, Ganesan Krishnan
Au-Ag alloy nanoparticles are physically synthesized using rapid, simple and efficient Q-switched Nd:YAG pulsed laser ablation in liquid technique (PLAL). Au and Ag colloidal solutions are separately prepared by 1064 nm laser ablation of metallic target (gold and silver) which is immersed in deionized water. Au-Ag alloy nanoparticles are prepared by irradiating the mixture of Au and Ag colloidal solutions with 532 nm of second harmonic wavelength of Nd:YAG laser at three different ratio, 3:1, 1:1 and 1:3 within different exposure times...
July 1, 2018: Journal of Nanoscience and Nanotechnology
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