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chemical shift

John M Egner, Davin R Jensen, Mike D Olp, Nolan W Kennedy, Brian F Volkman, Francis C Peterson, Brian C Smith, R Blake Hill
An academic chemical screening approach was developed and a 352-chemical fragment library screened against 3 different protein targets using 2D protein-detected NMR. The approach was optimized against 2 protein targets with known ligands, CXCL12 and BRD4. Principal component analysis reliably identified compounds that induced NMR crosspeak broadening, but did not unambiguously identify ligands with specific affinity (hits). For improved hit detection, a novel scoring metric - difference intensity analysis (DIA) - was devised that sums all positive and negative intensities from 2D difference spectra...
December 13, 2017: Chembiochem: a European Journal of Chemical Biology
Li Xu, Yangyang Duanmu, Glen M Blake, Chenxin Zhang, Yong Zhang, Keenan Brown, Xiaoqi Wang, Peng Wang, Xingang Zhou, Manling Zhang, Chao Wang, Zhe Guo, Giuseppe Guglielmi, Xiaoguang Cheng
OBJECTIVES: This study aimed to validate the accuracy and reliability of quantitative computed tomography (QCT) and chemical shift encoded magnetic resonance imaging (CSE-MRI) to assess hepatic steatosis. METHODS: Twenty-two geese with a wide range of hepatic steatosis were collected. After QCT and CSE-MRI examinations, the liver of each goose was removed and samples were taken from the left lobe, upper and lower half of the right lobe for biochemical measurement and histology...
December 13, 2017: European Radiology
Sergei Kirischuk, Anne Sinning, Oriane Blanquie, Jenq-Wei Yang, Heiko J Luhmann, Werner Kilb
Animal and human studies revealed that patterned neuronal activity is an inherent feature of developing nervous systems. This review summarizes our current knowledge about the mechanisms generating early electrical activity patterns and their impact on structural and functional development of the cerebral cortex. All neocortical areas display distinct spontaneous and sensory-driven neuronal activity patterns already at early phases of development. At embryonic stages, intermittent spontaneous activity is synchronized within small neuronal networks, becoming more complex with further development...
2017: Frontiers in Cellular Neuroscience
Przemysław J Boratyński
Scoring permutations of experimental chemical shift deviations and DFT/GIAO calculated deviations of isotropic shieldings for sets of four diastereomers can help to assign their relative configurations. This method was exercised on a set of diastereomeric Cinchona alkaloid derivatives, where 13C NMR data always identified the proper configuration. The presented approach is also an attempt to quantify the assignment by exclusion.
2017: Beilstein Journal of Organic Chemistry
M C Alamar, Roberta Tosetti, Sandra Landahl, Antonio Bermejo, Leon A Terry
Potatoes represent an important staple food crop across the planet. Yet, to maintain tuber quality and extend availability, there is a necessity to store tubers for long periods often using industrial-scale facilities. In this context, preserving potato quality is pivotal for the seed, fresh and processing sectors. The industry has always innovated and invested in improved post-harvest storage. However, the pace of technological change has and will continue to increase. For instance, more stringent legislation and changing consumer attitudes have driven renewed interest in creating alternative or complementary post-harvest treatments to traditional chemically reliant sprout suppression and disease control...
2017: Frontiers in Plant Science
Kevin Reiter, Fabian Mack, Florian Weigend
We present a highly efficient implementation for density functional calculations of chemical shielding constants. It employs the multipole-accelerated resolution of the identity for the calculation of the Coulomb part, which complements the usage of low order scaling routines for the evaluation of the exchange-correlation part and the Hartree-Fock exchange part. Introduced errors for shifts of chemical shielding constants of H, C, F and P are evaluated for respective test sets of molecules and are related to the accuracy of shifts obtained with hybrid and non-hybrid functionals of the generalized gradient approximation type as well as for meta-GGA functionals themselves, also considering solvation effects...
December 12, 2017: Journal of Chemical Theory and Computation
Andrea Sciutto, Andrea Fermi, Andrea Folli, Tommaso Battisti, Joseph Beames, Damien Murphy, Davide Bonifazi
Here we describe the synthesis of electron-rich PXX derivatives in which the energy levels of the excited states have been tailored through the insertion of imide groups. This has allowed the development of a new series of oxygen-doped photoredox-active chromophores with improved oxidizing and reducing properties. Capitalizing on the dehalogenation of organic halides as a model reaction, we could investigate the photooxidative and photoreductive potential of these molecules in model chemical transformations...
December 12, 2017: Chemistry: a European Journal
Veera Mohana Rao Kakita, Jagadeesh Bharatam
The present manuscript reports development and applications of real-time homonuclear broadband decoupled pure shift version of in-phase zero-quantum filtered COSY (PS-IPZF-COSY) and clean in-phase COSY (PS-CLIP-COSY) pulse schemes. In contrast to the conventional COSY schemes, these PS-versions provide enhanced spectral resolution and simplify the chemical shift correlation analysis of scalar coupled spins in complex organic molecules, which are exemplified for erythromycin A, estradiol and a mixture of estradiol and testosterone...
December 12, 2017: Magnetic Resonance in Chemistry: MRC
Sandeep Kumar Mishra, N Suryaprakash
The limited chemical shift range of protons and pairwise interaction among all the abundant nuclear spins of a molecule make 1 H spectrum too complicated. As a consequence the straightforward analysis and the accurate extraction of their interaction strengths from the 1 H spectrum of a complex spin system is formidably difficult or often impossible. This problem persists in the determination of scalar couplings be it between two abundant homonuclear spins or between 1 H and an abundant heteronuclear spin (viz...
December 12, 2017: Magnetic Resonance in Chemistry: MRC
Adrianus J Bakermans, Jason N Bazil, Aart J Nederveen, Gustav J Strijkers, S Matthijs Boekholdt, Daniel A Beard, Jeroen A L Jeneson
Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) is a unique non-invasive imaging modality for probing in vivo high-energy phosphate metabolism in the human heart. We investigated whether current 31P-MRS methodology would allow for clinical applications to detect exercise-induced changes in (patho-)physiological myocardial energy metabolism. Hereto, measurement variability and repeatability of three commonly used localized 31P-MRS methods [3D image-selected in vivo spectroscopy (ISIS) and 1D ISIS with 1D chemical shift imaging (CSI) oriented either perpendicular or parallel to the surface coil] to quantify the myocardial phosphocreatine (PCr) to adenosine triphosphate (ATP) ratio in healthy humans (n = 8) at rest were determined on a clinical 3 Tesla MR system...
2017: Frontiers in Physiology
Mahima Sharma, Gagan D Gupta, Vinay Kumar
The activated binary toxin (BinAB) from Lysinibacillus sphaericus binds to surface receptor protein (Cqm1) on the midgut cell membrane and kills Culex quinquefasciatus larvae on internalization. Cqm1 is attached to cells via a glycosyl-phosphatidylinositol (GPI) anchor. It has been classified as a member of glycoside hydrolase family 13 of the CAZy database. Here, we report characterization of the ordered domain (residues 23-560) of Cqm1. Gene expressing Cqm1 of BinAB susceptible mosquito was chemically synthesized and the protein was purified using E...
December 8, 2017: Insect Biochemistry and Molecular Biology
Lucas R Parent, Evangelos Bakalis, Maria Proetto, Yiwen Li, Chiwoo Park, Francesco Zerbetto, Nathan C Gianneschi
Revolutions in science and engineering frequently result from the development, and wide adoption, of a new, powerful characterization or imaging technique. Beginning with the first glass lenses and telescopes in astronomy, to the development of visual-light microscopy, staining techniques, confocal microscopy, and fluorescence super-resolution microscopy in biology, and most recently aberration-corrected, cryogenic, and ultrafast (4D) electron microscopy, X-ray microscopy, and scanning probe microscopy in nanoscience...
December 11, 2017: Accounts of Chemical Research
D J Srivastava, P Florian, J H Baltisberger, P J Grandinetti
The dependence of a 29Si geminal J coupling across the inter-tetrahedral linkage on local structure was examined using first-principles DFT calculations. The two main influences on 2JSi-O-Si were found to be a primary dependence on the linkage Si-O-Si angle and a secondary dependence on mean Si-O-Si linkage of the two coupled 29Si nuclei. An analytical expression describing these dependences was proposed and used to develop an approach for relating the correlated pair of 2JSi-O-Si coupling and mean 29Si isotropic chemical shift to the linkage Si-O-Si angle and the mean Si-O-Si angle of the two coupled 29Si nuclei...
December 11, 2017: Physical Chemistry Chemical Physics: PCCP
Katharina Anna Lindlbauer, Hans Marx, Michael Sauer
Background: In their quest for sustainable development and effective management of greenhouse gas emissions, our societies pursue a shift away from fossil-based resources towards renewable resources. With 95% of our current transportation energy being petroleum based, the application of alternative, carbon-neutral products-among them biodiesel-is inevitable. In order to enhance the cost structure of biodiesel biorefineries, the valorization of the crude glycerol waste stream into high-value platform chemicals is of major importance...
2017: Biotechnology for Biofuels
Justin Liam Henri, Joanna Macdonald, Mia Strom, Wei Duan, Sarah Shigdar
Current therapy for ovarian cancer typically involves indiscriminate chemotherapies that can have severe off target effects on healthy tissue and are still plagued by aggressive recurrence. Recent shifts towards targeted therapies offer the possibility of circumventing the obstacles experienced by these traditional treatments. While antibodies are the pioneering agents in targeted therapies, clinical experience has demonstrated that their antitumor efficacy is limited due to their high immunogenicity, large molecular size, and costly and laborious production...
December 7, 2017: Biochimie
Moo-Yeal Lee, Parnian Bigdelou, Kyung-Jin Hong, Kyoung-Ae Kim, Yoshitsune Shinya, Toshio Kajiuchi
Horseradish peroxidase was chemically modified with comb-shaped polymaleic anhydride-alt-1-tetradecene (PMA-TD) in microemulsion systems to produce surface-active peroxidase that has capability to form micellar structures in aqueous solutions and can be concentrated at liquid/liquid interfaces without unfolding of the enzyme. For chemical modification oil-in-water (O/W) and water-in-oil (W/O) microemulsion systems composed of n-butyl acetate and a buffer solution were prepared because n-butyl acetate turned out to be less detrimental to the activity of peroxidase at high degree of modification compared to other organic solvents...
February 2018: Enzyme and Microbial Technology
Fabien Kieken, Karine Loth, Nico van Nuland, Peter Tompa, Tom Lenaerts
Src Homology 2 and 3 (SH2 and SH3) are two key protein interaction modules involved in regulating the activity of many proteins such as tyrosine kinases and phosphatases by respective recognition of phosphotyrosine and proline-rich regions. In the Src family kinases, the inactive state of the protein is the direct result of the interaction of the SH2 and the SH3 domain with intra-molecular regions, leading to a closed structure incompetent with substrate modification. Here, we report the 1H, 15N and 13C backbone- and side-chain chemical shift assignments of the partially deuterated Fyn SH3-SH2 domain and structural differences between tandem and single domains...
December 9, 2017: Biomolecular NMR Assignments
Sam Osseiran, Elisabeth M Roider, Hequn Wang, Yusuke Suita, Michael Murphy, David E Fisher, Conor L Evans
Chemical sun filters are commonly used as active ingredients in sunscreens due to their efficient absorption of ultraviolet (UV) radiation. Yet, it is known that these compounds can photochemically react with UV light and generate reactive oxygen species and oxidative stress in vitro, though this has yet to be validated in vivo. One label-free approach to probe oxidative stress is to measure and compare the relative endogenous fluorescence generated by cellular coenzymes nicotinamide adenine dinucleotides and flavin adenine dinucleotides...
December 2017: Journal of Biomedical Optics
Maxim Gawrilow, Helmut Beckers, Sebastian Riedel, Lan Cheng
A joint experimental-computational study of the molecular structure and vibrational spectra of the XeF6 molecule is reported. The vibrational frequencies, intensities and in particular the isotopic frequency shifts of the vibrational spectra for 129XeF6 and 136XeF6 isotopologues recorded in the neon matrix agree very well with those obtained from relativistic coupledcluster calculations for XeF6 in the C3v structure, thereby strongly support the observation of the C3v conformer of the XeF6 molecule in the neon matrix...
December 8, 2017: Journal of Physical Chemistry. A
Julia L Kaszycki, Matthew A Baird, Alexandre A Shvartsburg
Nearly all compounds comprise numerous isotopologues ensuing from stable natural isotopes for constituent elements. The consequent isotopic envelopes in mass spectra can reveal the ion stoichiometry, but not geometry. We found those enve-lopes to split in differential ion mobility spectra obtained at high electric fields in a manner dependent on the ion geometry and buffer gas composition. The resulting multidimensional matrix of isotopic shifts is specific to structural isomers, provid-ing a fundamentally new approach to the characterization of chemical structure...
December 8, 2017: Analytical Chemistry
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