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Ke Sherry Li, Liuqing Shi, Michael L Gross
Assessment of protein structure and interaction is crucial for understanding protein structure/function relationships. Compared to high-resolution structural tools, including X-ray crystallography, nuclear magnetic resonance (NMR), and cryo-EM, and traditional low-resolution methods, such as circular dichroism, UV-vis, and florescence spectroscopy, mass spectrometry (MS)-based protein footprinting affords medium-to-high resolution (i.e., regional and residue-specific insights) by taking advantage of proteomics methods focused on the primary structure...
February 16, 2018: Accounts of Chemical Research
Xing Wang, Harro A J Meijer
The stable isotopes of water are extensively used as tracers in many fields of research. For this use, it is essential to know the isotope fractionation factors connected to various processes, the most important of which being phase changes. Many experimental studies have been performed on phase change fractionation over the last decades. Whereas liquid-vapour fractionation measurements are relatively straightforward, vapour-solid and liquid-solid fractionation measurements are more complicated, as maintaining equilibrium conditions when a solid is involved is difficult...
February 15, 2018: Isotopes in Environmental and Health Studies
Martino V Franchi, Severin Ruoss, Paola Valdivieso, Kyle W Mitchell, Kenneth Smith, Philip J Atherton, Marco V Narici, Martin Flück
AIMS: We assessed focal adhesion kinase (FAK) response to concentric (CON) versus eccentric (ECC) resistance training (RT) at two vastus lateralis (VL) sites, and the relationships between FAK, muscle protein synthesis (MPS), and morphological remodeling. METHODS: Six young males trained both legs unilaterally 3 times/week for 8 weeks; one leg performed CON RT, the contralateral performed ECC RT. Muscle biopsies were collected after training from VL midbelly (MID) and distal (Distal) sites at 0, 4, 8 weeks...
February 13, 2018: Acta Physiologica
Jingjie Mo, Renzhe Jin, Qingrong Yan, Izabela Sokolowska, Michael J Lewis, Ping Hu
Glycation has been observed in antibody therapeutics manufactured by the fed-batch fermentation process. It not only increases the heterogeneity of antibodies, but also potentially affects product safety and efficacy. In this study, non-glycated and glycated fractions enriched from a monoclonal antibody (mAb1) as well as glucose-stressed mAb1 were characterized using a variety of biochemical, biophysical and biological assays to determine the effects of glycation on the structure and function of mAb1. Glycation was detected at multiple lysine residues and reduced the antigen binding activity of mAb1...
February 13, 2018: MAbs
Ava Behnia, Mahmood A Fard, Johanna M Blacquiere, Richard J Puddephatt
A bidentate nitrogen-donor ligand with an appended phenol group, C5H4NCH[double bond, length as m-dash]N-2-C6H4OH, H(L1) was treated with a palladium cycloneophyl complex [Pd(CH2CMe2C6H4)(COD)], with both Pd-aryl and Pd-alkyl bonds, to give a Pd-alkyl complex, [Pd(CH2CMe2C6H5)(κ3-N,N',O-OC6H4N[double bond, length as m-dash]CH(2-C5H4N))], 1. The cleavage of the Pd-aryl bond and the deprotonation of the ligand phenol to afford a bound aryloxide, indicates facile Pd-aryl bond protonolysis. Deuterium labelling experiments confirmed that the ligand phenol promotes protonolysis and that the reverse, aryl C-H activation, occurs under very mild reaction conditions (within 10 min at room temperature)...
February 13, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Houda Ben Jemaa, Amani Mankaï, Sarra Khlifi, Rim Minaoui, Dhekra Ghozzi, Manel Zediri, Belhassen Kortobi, Inchirah Karmous, Halima Ben Hmad, Fethi Ben Slama, Henda Jamoussi, Hassan Aguenaou, Khalid El Kari, Abdallah Aouidet
BACKGROUND/OBJECTIVES: Accuracy of impedance analysis depends on population-specific prediction equations. The aim of this study was to propose new prediction equations to estimate body composition using impedance analysis for healthy Tunisian children and validate them using the deuterium oxide dilution (D2O) technique. SUBJECTS/METHODS: Body composition was estimated by the Tanita impedance analyzer. The validity of this system was investigated in 134 school children aged between 8 and 11 years...
February 8, 2018: Clinical Nutrition: Official Journal of the European Society of Parenteral and Enteral Nutrition
Kyle B Lynch, Yu Yang, Jiangtao Ren, Shaorong Liu
In recent years, much research has gone into developing online comprehensive two-dimensional liquid chromatographic systems allowing for high peak capacities in comparable separation times to that of one-dimensional liquid chromatographic systems. However, the speed requirements in the second dimension (2nd-D) still remain one challenge for complex biological samples due to the current configuration of two column/two detector systems. Utilization of multiple 2nd-D columns can mitigate this challenge. To adapt this approach, we need a multiple channel detector...
May 1, 2018: Talanta
Regina Adão, Letícia M Zanphorlin, Tatiani B Lima, Dev Sriranganadane, Käthe M Dahlström, Glaucia M S Pinheiro, Fabio C Gozzo, Leandro R S Barbosa, Carlos H I Ramos
Proteostasis is dependent on the Hsp70/Hsp90 system (the two chaperones and their co-chaperones). Of these, Hop (Hsp70/Hsp90 organizing protein), also known as Sti1, forms an important scaffold to simultaneously binding to both Hsp70 and Hsp90. Hop/Sti1 has been implicated in several disease states, for instance cancer and transmissible spongiform encephalopathies. Therefore, human and yeast homologous have been better studied and information on plant homologous is still limited, even though plants are continuously exposed to environmental stress...
February 6, 2018: Journal of Proteomics
Chen-Hao Wang, Anuvab Das, Wen-Yang Gao, David C Powers
Metal-organic frameworks (MOFs) have garnered substantial interest as platforms for site-isolated catalysis. Efficient diffusion of small molecule substrates to interstitial lattice-confined catalyst sites is critical to leveraging unique opportunities of these materials as catalysts. Understanding the rate of substrate diffusion in MOFs is challenging and few in situ chemical tools are available to evaluate substrate diffusion during interstitial MOF chemistry. Here, we demonstrate nitrogen-atom transfer (NAT) from a lattice-confined Ru2 nitride to toluene to generate benzylamine...
February 9, 2018: Angewandte Chemie
Shawn Sternisha, Peilu Liu, Alan G Marshall, Brian G Miller
Human glucokinase (GCK) acts as the body's primary glucose sensor and plays a critical role in glucose homeostatic maintenance. Gain-of-function mutations in gck produce hyperactive enzyme variants that cause congenital hyperinsulinism. Prior biochemical and biophysical studies suggest that activated disease variants can be segregated into two mechanistically distinct classes, termed α-type and β-type. Steady-state viscosity variation studies indicate that the kcat values of wild-type GCK and an α-type variant are partially diffusion-limited, whereas the kcat value of a β-type variant is viscosity-independent...
February 9, 2018: Biochemistry
Tobias Kromann-Hansen, Eva Louise Lange, Ida K Lund, Gunilla Høyer-Hansen, Peter A Andreasen, Elizabeth A Komives
The catalytic activity of trypsin-like serine proteases is in many cases regulated by conformational changes initiated by binding of physiological modulators to exosites located distantly from the active site. A trypsin-like serine protease of particular interest is urokinase-type plasminogen activator (uPA), which is involved in extracellular tissue remodeling processes. Herein, we used hydrogen/deuterium exchange mass spectrometry (HDXMS) to study regulation of activity in the catalytic domain of the murine version of uPA (muPA) by two muPA specific monoclonal antibodies...
2018: PloS One
Valerie A Schmidt, C Rose Kennedy, Máté J Bezdek, Paul J Chirik
The selective, intermolecular [1,4]-hydrovinylation of conjugated dienes with unactivated α-olefins catalyzed by α-diimine iron complexes is described. Value-added "skipped" diene products were obtained with exclusive [1,4]-selectivity, and the formation of branched, (Z)-olefin products was observed with no evidence for alkene isomerization. Mechanistic studies conducted with the well-defined, single-component iron precatalyst (MesDI)Fe(COD) (MesDI =[2,4,6-Me3-C6H2-N=CMe]2); COD = 1,5-cyclooctadiene) provided insights into the origin of the high selectivity...
February 7, 2018: Journal of the American Chemical Society
Rupesh Bommana, Qing Chai, Christian Schöneich, William F Weiss, Ranajoy Majumdar
This work compares the conformational stability, backbone flexibility, and aggregation propensity of monomer and dimer fractions of an IgG1 monoclonal antibody (mAb) generated upon UVA light exposure for up to 72 hours collected by preparative size-exclusion chromatography (SEC), compared to unstressed control. UVA light exposure induced covalent aggregation, and fragmentation as measured by SEC, sodium dodecyl sulfate polyacrylamide gel electrophoresis and extensive oxidation of specific methionine residues (Met 257, Met 433, and Met 109) in both size fractions identified by reverse phase chromatography coupled to mass spectrometry...
January 30, 2018: Journal of Pharmaceutical Sciences
Michael R Abel, Linda H Nie
PURPOSE: The purpose of this study is to develop and employ a Monte Carlo (MC) simulation model of associated particle neutron elemental imaging (APNEI) in order to determine the three-dimensional (3D) imaging resolution of such a system by examining relevant physical and technological parameters and to thereby begin to explore the range of clinical applicability of APNEI to fields such as medical diagnostics, intervention, and etiological research. METHODS: The presented APNEI model was defined in MCNP by a Gaussian-distributed and isotropic surface source emitting deuterium + deuterium (DD) neutrons, iron as the target element, nine iron-containing voxels (1 cm3 volume each) arranged in a 3-by-3 array as the interrogated volume of interest, and finally, by high-purity germanium (HPGe) gamma-ray detectors anterior and posterior to the 9-voxel array...
February 6, 2018: Medical Physics
Chao Shi, Xi Zhang, Chun-Hua Yu, Ye-Feng Yao, Wen Zhang
Deuteration of a hydrogen bond by replacing protium (H) with deuterium (D) can cause geometric changes in the hydrogen bond, known as the geometric H/D isotope effect (GIE). Understanding the GIEs on global structures and bulk properties is of great importance to study structure-property relationships of hydrogen-bonded systems. Here, we report a hydrogen-bonded host-guest crystal, imidazolium hydrogen terephthalate, that exemplifies striking GIEs on its hydrogen bonds, phases, and bulk dielectric transition property...
February 2, 2018: Nature Communications
Imane El Harchaoui, Asmaa El Hamdouchi, Issad Baddou, Imane El Menchawy, Kaoutar Benjeddou, Naima Saeid, Hakim Belghiti, Mohammed El Mzibri, Khalid El Kari, Hassan Aguenaou
BACKGROUND/OBJECTIVES: Estimating body composition using bioelectric impedance analysis (BIA) requires specific prediction equations. The purpose of our study was to examine the validity of published BIA equations for assessing total body water (TBW) and fat-free mass (FFM) using deuterium oxide dilution (D2O) as a reference method and to develop new FFM and TBW BIA equations if needed for Moroccan pre-pubertal children. SUBJECTS/METHODS: Data were collected from 247 schoolchildren aged 8-11 years old...
February 1, 2018: European Journal of Clinical Nutrition
Cameron J Owen, Georgia C Boles, Valeriy Chernyy, Joost M Bakker, P B Armentrout
A previous infrared multiple photon dissociation (IRMPD) action spectroscopy and density functional theory (DFT) study explored the structures of the [M,C,2H]+ products formed by dehydrogenation of methane by four, gas-phase 5d transition metal cations (M+ = Ta+, W+, Ir+, and Pt+). Complicating the analysis of these spectra for Ir and Pt was observation of an extra band in both spectra, not readily identified as a fundamental vibration. In an attempt to validate the assignment of these additional peaks, the present work examines the gas phase [M,C,2D]+ products of the same four metal ions formed by reaction with perdeuterated methane (CD4)...
January 28, 2018: Journal of Chemical Physics
Brian Mastracci, Wei Guo
The superfluid phase of helium-4, known as He ii, exhibits extremely small kinematic viscosity and may be a useful tool for economically producing and studying high Reynolds number turbulent flow. Such applications are not currently possible because a comprehensive understanding of the complex two-fluid behavior of He ii is lacking. This situation could be remedied by a systematic investigation of simple, well controlled turbulence that can be directly compared with theoretical models. To this end, we have developed a new apparatus that combines flow visualization with second sound attenuation to study turbulence in the wake of a mesh grid towed through a He ii filled channel...
January 2018: Review of Scientific Instruments
Philipp Högel, Alexander Götz, Felix Kuhne, Maximilian Ebert, Walter Stelzer, Kasper D Rand, Christina Scharnagl, Dieter Langosch
Flexible transmembrane helices frequently support the conformational transitions between different functional states of membrane proteins. While proline is well known to distort and destabilize transmembrane helices, the role of glycine is still debated. Here, we systematically investigated the effect of glycine on transmembrane helix flexibility by placing it at different sites within the otherwise uniform leucine/valine repeat sequence of the LV16 model helix. We show that amide deuterium/hydrogen exchange kinetics are increased near glycine...
February 1, 2018: Biochemistry
Jie Zhao, Helmut Beckers, Tengfei Huang, Xuefeng Wang, Sebastian Riedel
Laser-ablated boron atoms react with GeH4 molecules to form novel germylidene borane H2GeBH2, which undergoes a photochemical rearrangement to the germanium tetrahydroborate Ge(μ-H)2BH2 upon irradiation with light of λ = 405 nm. For comparison, the boron atom reactions with SnH4 only gave the tin tetrahydroborate Sn(μ-H)2BH2. Infrared matrix-isolation spectroscopy with deuterium substitution and the state-of-the-art quantum-chemical calculations are used to identify these species in solid argon. A planar structure of H2GeBH2 with an electron-deficient B-Ge bond with a partial multiple bond character (bond order = 1...
January 31, 2018: Inorganic Chemistry
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