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https://www.readbyqxmd.com/read/28437089/%C3%AF-n-c-bond-difunctionalization-in-bridged-twisted-amides-sew-and-cut-activation-approach-to-functionalized-isoquinolines
#1
Feng Hu, Pradeep Nareddy, Roger Lalancette, Frank Jordan, Michal Szostak
A rare example of highly selective σ N-C bond difunctionalization in bridged twisted lactams through N-C cleavage has been achieved. In combination with the intramolecular Heck cyclization, this method affords a two-step bond reorganization event ("sew-and-cut") to access functionalized isoquinoline ring systems directly with high atom economy. C-H bond functionalizations directed by a weakly coordinating bridged amide bond increase scaffold diversity. Preliminary mechanistic studies on the effect of amide distortion and the role of electrophile in this unusual σ N-C amide difunctionalization are described...
April 24, 2017: Organic Letters
https://www.readbyqxmd.com/read/28436526/structural-implications-on-the-excitation-dynamics-of-fluorescent-3h-indolium-cations
#2
Ek Raj Thapaliya, Jaume Garcia-Amorós, Santi Nonell, Burjor Captain, Françisco M Raymo
Fluorescent 3H-indolium cations are valuable components for the realization of activatable fluorophores for bioimaging applications. Their relatively poor fluorescent quantum yields in organic solvents, however, appear to be in contradiction to their good performance in analytical methods based on single-molecule detection. The elucidation of the structural factors governing the excitation dynamics of these compounds is, therefore, essential to rationalize these effects and possibly guide the future design of activatable probes with improved performance...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28436131/twisting-of-alkynes-towards-a-carbon-double-helix
#3
Abdulselam Adam, Gebhard Haberhauer
The carbon allotrope exhibiting only one-dimensional sp-hybridized carbon atoms is called carbyne. However, its existence is very controversially discussed. Studies regarding model compounds for carbyne revealed that many oligoalkynes show not a straight, but a bent structure of the carbon chain. Here we deal with the question whether it would also be possible to get a more complex structure from carbyne like a dimeric double helix. By means of quantum chemical calculations we were able to show that only a small energetic expense is needed for the formation of a double helix starting from oligoalkyne chains...
April 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28435837/staphylococcus-aureus-type-i-signal-peptidase-essential-or-not-essential-that-s-the-question
#4
COMMENT
Wouter L Hazenbos, Elizabeth Skippington, Man-Wah Tan
Secretion of proteins into the extracellular environment is crucial for the normal physiology and virulence of pathogenic bacteria. Type I signal peptidase (SPase I) mediates the final step of bacterial secretion, by cleaving proteins at their signal peptide once they are translocated by the Sec or twin-arginine (Tat) translocon. SPase I has long been thought to be essential for viability in multiple bacterial pathogens. Challenging this view, we and others have recently created Staphylococcus aureus bacteria lacking the SPase I SpsB that are viable and able to grow in vitro when over-expressing a native gene cassette encoding for a putative ABC transporter...
March 17, 2017: Microbial Cell
https://www.readbyqxmd.com/read/28435737/n-1-5-bromo-2-hy-droxy-phen-yl-ethyl-idene-isonicotinohydrazide-monohydrate-crystal-structure-and-hirshfeld-surface-analysis
#5
See Mun Lee, Nathan R Halcovitch, Mukesh M Jotani, Edward R T Tiekink
In the title isonicotinohydrazide hydrate, C14H12BrN3O2·H2O {systematic name: N'-[(1E)-1-(5-bromo-2-hy-droxy-phen-yl)ethyl-idene]pyridine-4-carbohydrazide monohydrate}, the central CN2O region of the organic mol-ecule is planar and the conformation about the imine-C=N bond is E. While an intra-molecular hy-droxy-O-H⋯N(imine) hydrogen bond is evident, the dihedral angle between the central residue and the benzene rings is 48.99 (9)°. Overall, the mol-ecule is twisted, as seen in the dihedral angle of 71...
April 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28435722/1-butyl-1-chloro-3-methyl-3h-2-1%C3%AE-4-benzoxa-tellurole-crystal-structure-and-hirshfeld-analysis
#6
Julio Zukerman-Schpector, Rodrigo Cunha, Álvaro T Omori, Lucas Sousa Madureira, Edward R T Tiekink
Two independent mol-ecules comprise the asymmetric unit in the title benzoxatellurole compound, C12H17ClOTe. The mol-ecules, with the same chirality at the methine C atom, are connected into a loosely associated dimer by Te⋯O inter-actions, leading to a {⋯Te-O}2 core. The resultant C2ClO2 donor set approximates a square pyramid with the lone pair of electrons projected to occupy a position trans to the n-butyl substituent. Inter-estingly, the Te(IV) atoms exhibit opposite chirality. The major difference between the independent mol-ecules relates to the conformation of the five-membered chelate rings, which is an envelope with the O atom being the flap, in one mol-ecule and is twisted about the O-C(methine) bond in the other...
April 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28435716/crystal-structure-of-4-5-di-bromo-phenanthrene
#7
Nicholas S Kim, Dasan M Thamattoor
The synthesis and crystal structure of the title compound, C14H8Br2, is described. The mol-ecule is positioned on a twofold rotation axis and the asymmetric unit consists of half a mol-ecule with the other half being generated by symmetry. The presence of two large bromine atoms in the bay region significantly distorts the mol-ecule from planarity and the mean planes of the two terminal rings of the phenanthrene system are twisted away from each other by 28.51 (14)°. The torsion angle between the two C-Br bonds is 74...
April 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28434914/full-length-oligomeric-structure-of-wzz-determined-by-cryoelectron-microscopy-reveals-insights-into-membrane-bound-states
#8
Richard F Collins, Vasileios Kargas, Brad R Clarke, C Alistair Siebert, Daniel K Clare, Peter J Bond, Chris Whitfield, Robert C Ford
Wzz is an integral inner membrane protein involved in regulating the length of lipopolysaccharide O-antigen glycans and essential for the virulence of many Gram-negative pathogens. In all Wzz homologs, the large periplasmic domain is proposed to be anchored by two transmembrane helices, but no information is available for the transmembrane and cytosolic domains. Here we have studied purified oligomeric Wzz complexes using cryoelectron microscopy and resolved the transmembrane regions within a semi-continuous detergent micelle...
April 11, 2017: Structure
https://www.readbyqxmd.com/read/28434241/-facilitating-role-of-traumatic-experiences-in-art
#9
József Gerevich
Traumatic experiences can not only have unfavourable consequences, they can also contribute, with a kind of creative twist, to the development of the person affected by the trauma. The artistic responses to traumas can be examined on the basis of the different types of trauma. This study reports on an investigation focusing on six types of trauma: emotional deprivation/neglect; near-death experience; becoming the victim of violence; war; accident/sickness and emotional frustration. Examples taken from the history of art indicate that works of art can draw attention to the traumatic experiences of the artists with frequently repeated motifs and portrayal techniques (sun, mother image, objects referring to the person lost, motifs of violence or symbols of violence, artistic manifestations of an exaggerated self-image, surreal visions, dry irony, substituting other objects for the beloved person), or a sudden change of style and subject that can express a heightened interest in human suffering (Lovis Corinth)...
April 2017: Orvosi Hetilap
https://www.readbyqxmd.com/read/28433578/a-novel-device-for-continuous-long-term-electroencephalogram-recording-and-drug-administration-in-mice-with-a-nice-powerful-and-sophisticated-wired-system
#10
Shigeru Watanabe, Masanori Saito, Masaki Soma, Hitoshi Miyaoka, Masami Takahashi
BACKGROUND: To elucidate mechanisms of epileptogenesis and epileptic maturation, and to develop new AEDs, it is indispensable to administer various drugs and to examine their effects on EEG over a long period of observation. NEW METHOD: We constructed a device for the continuous measurement of electroencephalography (EEG) and the infusion of anti-epileptic drugs over a prolonged period of time in moving mice. The system includes a slip ring and a swivel to prevent twisting of the recording cable and infusion tube, respectively...
April 19, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28432834/molecular-control-of-gut-formation-in-the-spider-parasteatoda-tepidariorum
#11
Natália Martins Feitosa, Matthias Pechmann, Evelyn E Schwager, Vitória Tobias-Santos, Alistair P McGregor, Wim G M Damen, Rodrigo Nunes da Fonseca
The development of a digestive system is an essential feature of bilaterians. Studies of the molecular control of gut formation in arthropods have been studied in detail in the fruit fly Drosophila melanogaster. However, little is known in other arthropods, especially in noninsect arthropods. To better understand the evolution of arthropod alimentary system, we investigate the molecular control of gut development in the spider Parasteatoda tepidariorum (Pt), the primary chelicerate model species for developmental studies...
April 22, 2017: Genesis: the Journal of Genetics and Development
https://www.readbyqxmd.com/read/28430504/topological-exciton-bands-in-moir%C3%A3-heterojunctions
#12
Fengcheng Wu, Timothy Lovorn, A H MacDonald
Moiré patterns are common in van der Waals heterostructures and can be used to apply periodic potentials to elementary excitations. We show that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moiré patterns that introduce twist-angle dependent satellite excitonic peaks. Topological exciton bands with nonzero Chern numbers that support chiral excitonic edge states can be engineered by combining three ingredients: (i) the valley Berry phase induced by electron-hole exchange interactions, (ii) the moiré potential, and (iii) the valley Zeeman field...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430456/the-microstructure-of-%C3%AE-sitosterol-%C3%AE-oryzanol-edible-organogels
#13
Andrew Barclay Matheson, Vasileios Koutsos, Georgios A Dalkas, Stephen Robert Euston, Paul S Clegg
Rheology and atomic force microscopy (AFM) were employed to examine the microstructure of β-sitosterol : γ-oryzanol organogels in sunflower oil. Using time resolved rheology we followed gel formation, paying specific attention to the fibril aggregation process, which had not been studied in detail previously for this system. Using AFM we observed gel structures directly, and obtained detailed information of the gel structure, far exceeding previous studies. Our analysis suggests that though gels are formed by the self-assembly and aggregation of one-dimensional fibrils, the manner in which these fibrils aggregate into ribbons results in complex structures of higher dimensionality...
April 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28426230/photophysics-and-excited-state-properties-of-cyclometalated-iridium-iii-platinum-ii-and-iridium-iii-iridium-iii-bimetallic-complexes-bridged-by-dipyridylpyrazine
#14
Yang-Jin Cho, So-Yoen Kim, Chang Min Choi, Nam Joon Kim, Chul Hoon Kim, Dae Won Cho, Ho-Jin Son, Chyongjin Pac, Sang Ook Kang
We investigated the electrochemical and excited-state properties of 2,3-bis(2-pyridyl)pyrazine (dpp)-bridged bimetallic complexes, (L)2Ir-dpp-PtCl [1, L = 2-(4',6'-difluorophenyl)pyridinato-N,C(2) (dfppy); 2, L = 2-phenylpyridinato-N,C(2) (ppy)] and [(L)2Ir]2(dpp) [3, L = dfppy; 4, L = ppy] compared to monometallic complexes, (L)2Ir-dpp (5, L = dfppy; 6, L = ppy) and dpp-PtCl (dpp-Pt(II)Cl2; 7). The single-crystal X-ray crystallographic structures of 1, 3, 5, and 6 showed that 1 and 3 have approximately coplanar structures of the dpp unit, while the noncoordinated pyridine ring of dpp in 5 and 6 is largely twisted with respect to the pyrazine ring...
April 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28423273/conformational-dynamics-of-mechanically-compliant-dna-nanostructures-from-coarse-grained-molecular-dynamics-simulations
#15
Ze Shi, Carlos E Castro, Gaurav Arya
Structural DNA nanotechnology, the assembly of rigid 3D structures of complex yet precise geometries, has recently been used to design dynamic, mechanically compliant nanostructures with tunable equilibrium conformations and conformational distributions. Here we use coarse-grained molecular dynamics simulations to provide insights into the conformational dynamics of a set of mechanically compliant DNA nanostructures-DNA hinges that use single-stranded DNA "springs" to tune the equilibrium conformation of a layered double-stranded DNA "joint" connecting two stiff "arms" constructed from DNA helix bundles...
April 24, 2017: ACS Nano
https://www.readbyqxmd.com/read/28422740/involvement-of-mir-106b-in-tumorigenic-actions-of-both-prolactin-and-estradiol
#16
Kuan-Hui Ethan Chen, Karissa Bustamante, Vi Nguyen, Ameae M Walker
Prolactin promotes a variety of cancers by an array of different mechanisms. Here, we have investigated prolactin's inhibitory effect on expression of the cell cycle-regulating protein, p21. Using a miRNA array, we identified a number of miRNAs upregulated by prolactin treatment, but one in particular that was strongly induced by prolactin and predicted to bind to the 3'UTR of p21 mRNA, miR-106b. By creating a p21 mRNA 3'UTR-luciferase mRNA construct, we demonstrated degradation of the construct in response to prolactin in human breast, prostate and ovarian cancer cell lines...
March 31, 2017: Oncotarget
https://www.readbyqxmd.com/read/28422222/electron-transfer-in-silicon-bridged-adjacent-chromophores-the-source-for-blue-green-emission
#17
Malgorzata Bayda, Gonzalo Angulo, Gordon L Hug, Monika Ludwiczak, Jerzy Karolczak, Jacek Koput, Jacek Dobkowski, Bronislaw Marciniak
Si-Bridged chromophores have been proposed as sources for blue-green emission in several technological applications. The origin of this dual emission is to be found in an internal charge transfer reaction. The current work is an attempt to describe the details of these processes in these kinds of substances, and to design a molecular architecture to improve their performance. Nuclear motions essential for intramolecular charge transfer (ICT) can involve processes from twisted internal moieties to dielectric relaxation of the solvent...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28421501/chapter-17-sterile-plate-based-vitrification-of-adherent-human-pluripotent-stem-cells-and-their-derivatives-using-the-twist-method
#18
Julia C Neubauer, Frank Stracke, Heiko Zimmermann
Due to their high biological complexity, e.g., their close cell-to-cell contacts, cryopreservation of human pluripotent stem cells with standard slow-rate protocols often is inefficient and can hardly be standardized. Vitrification that means ultrafast freezing already showed very good viability and recovery rates for this sensitive cell system, but is only applicable for low cell numbers, bears a high risk of contamination, and can hardly be implemented under GxP regulations. In this chapter, a sterile plate-based vitrification method for adherent pluripotent stem cells and their derivatives is presented based on a procedure and device for human embryonic stem cells developed by Beier et al...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28419165/soaking-suggests-alternative-facts-only-co-crystallization-discloses-major-ligand-induced-interface-rearrangements-of-a-homodimeric-trna-binding-protein-indicating-a-novel-mode-of-inhibition
#19
Frederik Rainer Ehrmann, Johann Stojko, Alexander Metz, François Debaene, Luzi Jakob Barandun, Andreas Heine, François Diederich, Sarah Cianférani, Klaus Reuter, Gerhard Klebe
For the efficient pathogenesis of Shigella, the causative agent of bacillary dysentery, full functionality of tRNA-guanine transglycosylase (TGT) is mandatory. TGT performs post-transcriptional modifications of tRNAs in the anticodon loop taking impact on virulence development. This suggests TGT as a putative target for selective anti-shigellosis drug therapy. Since bacterial TGT is only functional as homodimer, its activity can be inhibited either by blocking its active site or by preventing dimerization. Recently, we discovered that in some crystal structures obtained by soaking the full conformational adaptation most likely induced in solution upon ligand binding is not displayed...
2017: PloS One
https://www.readbyqxmd.com/read/28418950/sacral-fatigue-fracture-in-a-military-recruit
#20
Matthew D Burgess, Mickaila J Johnston, Eugene D Silverman
A 19-year-old male military recruit presented with 3 weeks of persistent left hip and groin pain after abnormally twisting his hip during a hike. Initial radiographs were interpreted as negative. He subsequently underwent a bone scan which revealed linear left sacral uptake along or paralleling the sacroiliac joint. Differential diagnostic considerations included unilateral sacroiliitis and sacral fracture. SPECT/CT was performed which confirmed left sacral fatigue stress fracture. Transitional lumbosacral anatomy was evident on radiographs with pseudoarticulation of the transitional left S1 transverse process with the sacrum...
April 17, 2017: Clinical Nuclear Medicine
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