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https://www.readbyqxmd.com/read/27913993/antifreeze-glycopeptides-from-structure-and-activity-studies-to-current-approaches-in-chemical-synthesis
#1
REVIEW
Małgorzata Urbańczyk, Jerzy Góra, Rafał Latajka, Norbert Sewald
Antifreeze glycopeptides (AFGPs) are a class of biological antifreeze agents found predominantly in Arctic and Antarctic species of fish. They possess the ability to regulate ice nucleation and ice crystal growth, thus creating viable life conditions at temperatures below the freezing point of body fluids. AFGPs usually consist of 4-55 repetitions of the tripeptide unit Ala-Ala-Thr that is O-glycosylated at the threonine side chains with β-D-galactosyl-(1 → 3)-α-N-acetyl-D-galactosamine. Due to their interesting properties and high antifreeze activity, they have many potential applications, e...
December 2, 2016: Amino Acids
https://www.readbyqxmd.com/read/27913828/engineering-and-evolution-of-saccharomyces-cerevisiae-to-produce-biofuels-and-chemicals
#2
Timothy L Turner, Heejin Kim, In Iok Kong, Jing-Jing Liu, Guo-Chang Zhang, Yong-Su Jin
To mitigate global climate change caused partly by the use of fossil fuels, the production of fuels and chemicals from renewable biomass has been attempted. The conversion of various sugars from renewable biomass into biofuels by engineered baker's yeast (Saccharomyces cerevisiae) is one major direction which has grown dramatically in recent years. As well as shifting away from fossil fuels, the production of commodity chemicals by engineered S. cerevisiae has also increased significantly. The traditional approaches of biochemical and metabolic engineering to develop economic bioconversion processes in laboratory and industrial settings have been accelerated by rapid advancements in the areas of yeast genomics, synthetic biology, and systems biology...
December 3, 2016: Advances in Biochemical Engineering/biotechnology
https://www.readbyqxmd.com/read/27911933/driving-cells-to-the-desired-state-in-a-bimodal-distribution-through-manipulation-of-internal-noise-with-biologically-practicable-approaches
#3
Che-Chi Shu, Chen-Chao Yeh, Wun-Sin Jhang, Shih-Chiang Lo
The stochastic nature of gene regulatory networks described by Chemical Master Equation (CME) leads to the distribution of proteins. A deterministic bistability is usually reflected as a bimodal distribution in stochastic simulations. Within a certain range of the parameter space, a bistable system exhibits two stable steady states, one at the low end and the other at the high end. Consequently, it appears to have a bimodal distribution with one sub-population (mode) around the low end and the other around the high end...
2016: PloS One
https://www.readbyqxmd.com/read/27911786/geometry-induced-sequence-of-nanoscale-frank-kasper-and-quasicrystal-mesophases-in-giant-surfactants
#4
Kan Yue, Mingjun Huang, Ryan L Marson, Jinlin He, Jiahao Huang, Zhe Zhou, Jing Wang, Chang Liu, Xuesheng Yan, Kan Wu, Zaihong Guo, Hao Liu, Wei Zhang, Peihong Ni, Chrys Wesdemiotis, Wen-Bin Zhang, Sharon C Glotzer, Stephen Z D Cheng
Frank-Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails...
November 28, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27911484/platinum-complex-assemblies-as-luminescent-probes-and-tags-for-drugs-and-toxins-in-water
#5
Stephan Sinn, Frank Biedermann, Luisa De Cola
A reactive phosphorescent probe for aza-heterocyclic drugs and toxins was developed, affording a supramolecular emission-switch-on chemosensor in water. Complex formation of the heterocycles with a platinum(II) precursor proceeds readily at ambient conditions, allowing for facile analyte screening. 52 structurally diverse compounds were tested, out of which 23 pyridines, imidazole, and triazoles formed strongly emissive complex aggregates. Importantly, they all can be clearly distinguished from each other through a principal component analysis, but often already by simple visual inspection, e...
December 1, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27910948/improved-in-cell-structure-determination-of-proteins-at-near-physiological-concentration
#6
Teppei Ikeya, Tomomi Hanashima, Saori Hosoya, Manato Shimazaki, Shiro Ikeda, Masaki Mishima, Peter Güntert, Yutaka Ito
Investigating three-dimensional (3D) structures of proteins in living cells by in-cell nuclear magnetic resonance (NMR) spectroscopy opens an avenue towards understanding the structural basis of their functions and physical properties under physiological conditions inside cells. In-cell NMR provides data at atomic resolution non-invasively, and has been used to detect protein-protein interactions, thermodynamics of protein stability, the behavior of intrinsically disordered proteins, etc. in cells. However, so far only a single de novo 3D protein structure could be determined based on data derived only from in-cell NMR...
December 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27909995/solithromycin-a-novel-fluoroketolide-for-the-treatment-of-community-acquired-bacterial-pneumonia
#7
REVIEW
George G Zhanel, Erika Hartel, Heather Adam, Sheryl Zelenitsky, Michael A Zhanel, Alyssa Golden, Frank Schweizer, Bala Gorityala, Philippe R S Lagacé-Wiens, Andrew J Walkty, Alfred S Gin, Daryl J Hoban, Joseph P Lynch, James A Karlowsky
Solithromycin is a novel fluoroketolide developed in both oral and intravenous formulations to address increasing macrolide resistance in pathogens causing community-acquired bacterial pneumonia (CABP). When compared with its macrolide and ketolide predecessors, solithromycin has several structural modifications which increase its ribosomal binding and reduce its propensity to known macrolide resistance mechanisms. Solithromycin, like telithromycin, affects 50S ribosomal subunit formation and function, as well as causing frame-shift errors during translation...
December 1, 2016: Drugs
https://www.readbyqxmd.com/read/27908108/dual-hydrogen-bonding-motifs-in-complexes-formed-between-tropolone-and-formic-acid
#8
Deacon J Nemchick, Michael K Cohen, Patrick H Vaccaro
The near-ultraviolet π(*)←π absorption system of weakly bound complexes formed between tropolone (TrOH) and formic acid (FA) under cryogenic free-jet expansion conditions has been interrogated by exploiting a variety of fluorescence-based laser-spectroscopic probes, with synergistic quantum-chemical calculations built upon diverse model chemistries being enlisted to unravel the structural and dynamical properties of the pertinent ground [X̃(1)A(')] and excited [Ã(1)A(')π(*)π] electronic states. For binary TrOH ⋅ FA adducts, the presence of dual hydrogen-bond linkages gives rise to three low-lying isomers designated (in relative energy order) as INT, EXT1, and EXT2 depending on whether docking of the FA ligand to the TrOH substrate takes place internal or external to the five-membered reaction cleft of tropolone...
November 28, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27907178/characteristics-of-phytoplankton-biomass-primary-production-and-community-structure-in-the-modaomen-channel-pearl-river-estuary-with-special-reference-to-the-influence-of-saltwater-intrusion-during-neap-and-spring-tides
#9
Weihua Zhou, Jie Gao, Jianzu Liao, Ronggui Shi, Tao Li, Yajuan Guo, Aimin Long
In recent decades, increasing frequency and intensity of saltwater intrusion in the Modaomen Channel has threatened the freshwater supply in the surrounding cities of the Pearl River Estuary, and ulteriorly changed the environmental conditions of the estuarine waters. Phytoplankton biomass, primary production (PP) and species composition, as well as hydrological and chemical parameters were examined along a downstream transect in the Modaomen Channel during neap tide (NT) and spring tide (ST), when a strong saltwater intrusion event occurred in late September, 2011...
2016: PloS One
https://www.readbyqxmd.com/read/27907055/effect-of-glu12-his89-interaction-on-dynamic-structures-in-hiv-1-p17-matrix-protein-elucidated-by-nmr
#10
Yuta Konagaya, Rina Miyakawa, Masumi Sato, Akimasa Matsugami, Satoru Watanabe, Fumiaki Hayashi, Takanori Kigawa, Chiaki Nishimura
To test the existence of the salt bridge and stability of the HIV-1 p17 matrix protein, an E12A (mutated at helix 1) was established to abolish possible electrostatic interactions. The chemical shift perturbation from the comparison between wild type and E12A suggested the existence of an electrostatic interaction in wild type between E12 and H89 (located in helix 4). Unexpectedly, the studies using urea denaturation indicated that the E12A substitution slightly stabilized the protein. The dynamic structure of E12A was examined under physiological conditions by both amide proton exchange and relaxation studies...
2016: PloS One
https://www.readbyqxmd.com/read/27906345/grating-coupling-based-excitation-of-bloch-surface-waves-for-lab-on-fiber-optrodes
#11
Michele Scaravilli, Giuseppe Castaldi, Andrea Cusano, Vincenzo Galdi
In this paper, we investigate the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, after exploring an idealized, proof-of-principle grating-coupling-based scheme for on-tip excitation of BSWs, we focus on an alternative configuration that is more robust with respect to fabrication-related non-idealities. Subsequently, with a view towards label-free chemical and biological sensing, we present a specific design aimed at enhancing the sensitivity (in terms of wavelength shift) of the arising resonance with respect to changes in the refractive properties of the surrounding environment...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906228/holographic-imaging-with-a-hard-x-ray-nanoprobe-ptychographic-versus-conventional-phase-retrieval
#12
A-L Robisch, J Wallentin, A Pacureanu, P Cloetens, T Salditt
We have performed near-field x-ray imaging with simultaneous object and probe reconstruction. By an advanced ptychographic algorithm based on longitudinal and lateral translations, full-field images of nanoscale objects are reconstructed with quantitative contrast values, along with the extended wavefronts used to illuminate the objects. The imaging scheme makes idealizing assumptions on the probe obsolete, and efficiently disentangles phase shifts related to the object from the imperfections in the illumination...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27900822/stimulus-responsive-nanoparticles-and-associated-reversible-polymorphism-via-polymerization-induced-self-assembly-pisa
#13
Yiwen Pei, Andrew B Lowe, Peter J Roth
Polymerization-induced self-assembly (PISA) is an extremely versatile method for the in situ preparation of soft-matter nanoparticles of defined size and morphologies at high concentrations, suitable for large-scale production. Recently, certain PISA-prepared nanoparticles have been shown to exhibit reversible polymorphism ("shape-shifting"), typically between micellar, worm-like, and vesicular phases (order-order transitions), in response to external stimuli including temperature, pH, electrolytes, and chemical modification...
November 30, 2016: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/27900626/selection-of-chemically-defined-media-for-cho-cell-fed-batch-culture-processes
#14
Xiao Pan, Mathieu Streefland, Ciska Dalm, René H Wijffels, Dirk E Martens
Two CHO cell clones derived from the same parental CHO(BC®) cell line and producing the same monoclonal antibody (BC-G, a low producing clone; BC-P, a high producing clone) were tested in four basal media in all possible combinations with three feeds (=12 conditions) in fed-batch cultures. Higher amino acid feeding did not always lead to higher mAb production. The two clones showed differences in cell physiology, metabolism and optimal medium-feed combinations. During the phase transitions of all cultures, cell metabolism showed a shift represented by lower specific consumption and production rates, except for the specific glucose consumption rate in cultures fed by Actifeed A/B...
November 29, 2016: Cytotechnology
https://www.readbyqxmd.com/read/27900379/a-theoretical-study-on-the-unusual-square-planar-structure-of-bis-imino-pyridine-ligated-group-13-complexes
#15
Weiyi Li, Yajing Lyu, Huifang Zhang, Maoqin Zhu, Hanping Tang
The unusual square-planar (SP) structure of four-coordinate Al(III)-complexes with the phenyl-substituted tridentate bis(imino)pyridine ((Ph)I2P) ligand has been studied by a combination of density functional theory (DFT) calculations, frontier molecule orbital (FMO), nucleus-independent chemical shift (NICS) and strain/interaction analyses. The calculations disclose that: (i) the aromaticity shifting from the pyridine ring to the alumina-imidazolate metallacycle, and (ii) the small strain energy imposed on the ligand backbone are two favourable factors for driving the overall SP coordination of the Al(III) ion...
November 30, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27898701/assessing-white-matter-microstructure-in-brain-regions-with-different-myelin-architecture-using-mri
#16
Samuel Groeschel, Gisela E Hagberg, Thomas Schultz, Dávid Z Balla, Uwe Klose, Till-Karsten Hauser, Thomas Nägele, Oliver Bieri, Thomas Prasloski, Alex L MacKay, Ingeborg Krägeloh-Mann, Klaus Scheffler
OBJECTIVE: We investigate how known differences in myelin architecture between regions along the cortico-spinal tract and frontal white matter (WM) in 19 healthy adolescents are reflected in several quantitative MRI parameters that have been proposed to non-invasively probe WM microstructure. In a clinically feasible scan time, both conventional imaging sequences as well as microstructural MRI parameters were assessed in order to quantitatively characterise WM regions that are known to differ in the thickness of their myelin sheaths, and in the presence of crossing or parallel fibre organisation...
2016: PloS One
https://www.readbyqxmd.com/read/27897362/unambiguous-determination-of-protein-arginine-ionization-states-in-solution-by-nmr-spectroscopy
#17
Yuichi Yoshimura, Nur Alia Oktaviani, Kento Yonezawa, Hironari Kamikubo, Frans A A Mulder
Because arginine residues in proteins are expected to be in their protonated form almost without exception, reports demonstrating that a protein arginine residue is charge-neutral are rare and potentially controversial. Herein, we present a (13) C-detected NMR experiment for probing individual arginine residues in proteins notwithstanding the presence of chemical and conformational exchange effects. In the experiment, the (15) N(η) and (15) N(ϵ) chemical shifts of an arginine head group are correlated with that of the directly attached (13) C(ζ) ...
November 29, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27897361/soluble-graphene-nanoribbons-from-planarization-of-oligophenylenes
#18
Choong Ping Sen, Suresh Valiyaveettil
A solution-based chemical synthesis of two graphene nanoribbons with armchair edge is reported. The precursor oligophenylene molecules were synthesized and subjected to oxidative cyclodehydrogenation to afford target molecules, G-1 and G-2. These molecules have good solubility in organic solvents, and showed a large red-shift in absorption edge (up to 185 nm) and emission maximum (up to 125 nm) after planarization. Fibrous structures were formed through self-assembly of molecules via columnar π - π stacking...
November 29, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27897294/synthesis-of-a-lithium-cyclopentadienide-complex-by-addition-of-lintf2-to-a-zwitterionic-fulvalene
#19
Dominic Schmid, Alexander Seyboldt, Klaus Eichele, Doris Kunz
The synthesis of a η(5)-coordinated LiCp complex by simple addition of a Li-salt in benzene is presented. A strongly zwitterionic fulvalene serves as the Cp-precursor. Evidence for the coordination of Li(+) was obtained by the characterisitic (7)Li NMR chemical shifts, variable temperature experiments in solution and by X-ray structure analysis in the solid state.
November 29, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27895820/sleep-circadian-dysrhythmia-obesity-and-diabetes
#20
REVIEW
Gumpeny Ramachandra Sridhar, Narasimhadevara Santhi Nirmala Sanjana
Synchrony of biological processes with environmental cues developed over millennia to match growth, reproduction and senescence. This entails a complex interplay of genetic, metabolic, chemical, light, hormonal and hedonistic factors across life forms. Sleep is one of the most prominent rhythms where such a match is established. Over the past 100 years or so, it has been possible to disturb the synchrony between sleep-wake cycle and environmental cues. Development of electric lights, shift work and continual accessibility of the internet has disrupted this match...
November 15, 2016: World Journal of Diabetes
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