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https://www.readbyqxmd.com/read/28644628/stereoelectronics-of-the-hydrogen-bond-induced-fluorescence-quenching-of-3-aminofluorenones-with-alcohols
#1
Isaac G Alty, Christopher John Abelt
Two derivatives of 3-amino-9-fluorenone (1) bearing one (2) and two methyl (3) groups flanking carbonyl group are prepared. Comparison of their photophysical properties show that all suffer efficient radiationless deactivation in the presence of alcohols. Preferential solvation studies with mono alcohols reveal that a single H-bonding interaction quenches the excited states of 1 and 2, but not that of 3. In contrast, a single molecule of ethylene glycol quenches all three. These results are interpreted in a quenching mechanism similar to one proposed by Inoue and coworkers, but where an out-of-plane H-bond with the carbonyl group gives rise to an emissive species, while an in-plane H-bond results in quenching...
June 23, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28644550/biphasic-liquid-crystal-and-the-simultaneous-measurement-of-isotropic-and-anisotropic-parameters-by-spatially-resolved-nmr-spectroscopy
#2
Malin Reller, Svenja Wesp, Martin R M Koos, Michael Knut Reggelin, Burkhard Luy
Residual dipolar couplings and other anisotropic NMR parameters are powerful tools for molecular structure elucidation when conventional techniques do not suffice. With current liquid crystalline preparations, it is necessary to prepare two samples to extract isotropic and anisotropic data from spectra and to derive the residual dipolar couplings. Here, we present the preparation, measurement, and interpretation of a novel biphasic liquid crystalline phase where a single sample can be used to generate both isotropic and anisotropic data...
June 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28644463/hypersensitive-dual-function-luminescence-switching-of-a-silver-chalcogenolate-cluster-based-metal-organic-framework
#3
Ren-Wu Huang, Yong-Sheng Wei, Xi-Yan Dong, Xiao-Hui Wu, Chen-Xia Du, Shuang-Quan Zang, Thomas C W Mak
Silver(i) chalcogenide/chalcogenolate clusters are promising photofunctional materials for sensing, optoelectronics and solar energy harvesting applications. However, their instability and poor room-temperature luminescent quantum yields have hampered more extensive study. Here, we graft such clusters to adaptable bridging ligands, enabling their interconnection and the formation of rigid metal-organic frameworks. By controlling the spatial separation and orientation of the clusters, they then exhibit enhanced stability (over one year) and quantum yield (12...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644017/spectrally-undiscerned-isomers-might-lead-to-erroneous-determination-of-water-exchange-rates-of-paracest-eu-iii-agents
#4
Nevenka Cakić, Ben Tickner, Moritz Zaiss, David Esteban-Gómez, Carlos Platas-Iglesias, Goran Angelovski
We report a detailed study of the solution structure and water exchange rate of a Eu(III) complex with the cyclen-based ligand L(1), containing (S)-2-(2-acetamido)-3-(4-(trifluoromethyl)phenyl)propanoate pendant arms at positions 1 and 7 of the cyclen ring and acetylglycinate pendants at positions 4 and 10. The EuL(1) complex was characterized by a combination of NMR and luminescence spectroscopy and density functional theory (DFT) calculations. The chemical exchange saturation transfer (CEST) spectra obtained at different temperatures and saturation powers present a CEST signal attributed to the coordinated water molecule...
June 23, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28643869/mechanotransduction-properties-of-the-cytoplasmic-tail-of-pecam-1
#5
Jessica L Snyder, Elena McBeath, Tamlyn N Thomas, Yi Jen Chiu, Robert L Clark, Keigi Fujiwara
BACKGROUND: Vascular endothelial cells (ECs) are a well-known cell system used in the study of mechanobiology. Using cultured ECs, we found that platelet endothelial cell adhesion molecule 1 (PECAM-1, CD31), a cell adhesion protein localized to regions of EC-EC contact, was rapidly tyrosine phosphorylated in ECs exposed to shear or cyclic stretch. Src-homology 2 domain-containing protein tyrosine phosphatase 2 (SHP2) binds phosphorylated PECAM-1 and activates the extracellular signal-regulated kinase1/2 (ERK1/2) signaling cascade, a known flow-activated signaling pathway...
June 23, 2017: Biology of the Cell
https://www.readbyqxmd.com/read/28643788/terahertz-saturable-absorbers-from-liquid-phase-exfoliation-of-graphite
#6
Vezio Bianchi, Tian Carey, Leonardo Viti, Lianhe Li, Edmund H Linfield, A Giles Davies, Alessandro Tredicucci, Duhee Yoon, Panagiotis G Karagiannidis, Lucia Lombardi, Flavia Tomarchio, Andrea C Ferrari, Felice Torrisi, Miriam S Vitiello
Saturable absorbers (SA) operating at terahertz (THz) frequencies can open new frontiers in the development of passively mode-locked THz micro-sources. Here we report the fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite. Open-aperture z-scan measurements with a 3.5 THz quantum cascade laser show a transparency modulation ∼80%, almost one order of magnitude larger than that reported to date at THz frequencies...
June 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28643473/can-the-propensity-of-protein-crystallization-be-increased-by-using-systematic-screening-with-metals
#7
REVIEW
Raghurama P Hegde, Pavithra G Chinnaswamy, Debayan Dey, Steven C Almo, S Ramakumar, Udupi A Ramagopal
Protein crystallization is one of the major bottlenecks in protein structure elucidation with new strategies being constantly developed to improve the chances of crystallization. Generally, well-ordered epitopes possessing complementary-surface and capable of producing stable inter-protein interactions generate a regular three-dimensional arrangement of protein molecules which eventually results in a crystal lattice. Metals, when used for crystallization, with their various coordination numbers and geometries, can generate such epitopes mediating protein oligomerization and/or establish crystal contacts...
June 23, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28643461/single-enzyme-biofuel-cells
#8
Chao Ji, Jingwei Hou, Kai Wang, Yun Hau Ng, Vicki Chen
Here, we firstly demonstrate that the intramolecular electron transfer within signle enzyme molecule is an important alternative pathway which can be harnessed to generate electricity. By decoupling the redox reactions within a single type of enzyme (e.g., Trametes versicolor laccase), we harvested electricity efficiently from unconventional fuels including recalcitrant pollutants (e.g. bisphenol-A and hydroquinon) in a single-laccase biofuel cell. The intramolecular electron-harnessing concept was further demonstrated with other enzymes, including power generation during CO2 bioconversion to formate catalyzed by formate dehydrogenase from Candida boidinii...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28643445/a-novel-electrochemical-biosensor-with-dual-signal-outputs-toward-simultaneous-quantification-of-ph-and-o2-in-brain-upon-ischemia-and-in-tumor-during-cancer-therapy
#9
Li Liu, Fan Zhao, Wei Liu, Tong Zhu, Zh John Zhang, Chen Chen, Zhihui Dai, Huisheng Peng, Jun-Long Huang, Qin Hu, Wenbo Bu, Yang Tian
In this work, we develop a novel methodology for designing electrochemical biosensors with both current and potential signal outputs for simultaneous determination of two important species in the live systems. By designing a new molecule, Hemin-aminoferrocene (Hemin-Fc), we create a single electrochemical biosensor for simultaneous quantification of O2 and pH in brain upon ischemia and in tumor during cancer starvation therapy. The reduction peak current of Hemin group increases with rising concentrations of O2 from 1...
June 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28643000/interaction-of-the-interleukin-8-protein-with-a-sodium-dodecyl-sulfate-micelle-a-computer-simulation-study
#10
Hector Dominguez
Molecular simulations were carried out to study the sodium dodecyl sulfate (SDS) surfactant with the interleukin 8 (IL8) protein as a model to investigate the influence of amphiphilic molecules on proteins. Simulations for an SDS micelle with an IL8 protein show that both aggregates, which were initially separated, eventually approach each other to form a single complex. The results showed that the protein was attached to the SDS micelle by the charged positive amino acids whereas less contacts were observed for the negatively charged amino acids...
July 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/28642701/the-market-of-biopharmaceutical-medicines-a-snapshot-of-a-diverse-industrial-landscape
#11
Evelien Moorkens, Nicolas Meuwissen, Isabelle Huys, Paul Declerck, Arnold G Vulto, Steven Simoens
Background: Biopharmaceutical medicines represent a growing share of the global pharmaceutical market, and with many of these biopharmaceutical products facing loss of exclusivity rights, also biosimilars may now enter the biopharmaceutical market. Objectives: This study aims to identify and document which investment and development strategies are adopted by industrial players in the global biopharmaceutical market. Methods: A descriptive analysis was undertaken of the investment and development strategies of the top 25 pharmaceutical companies according to 2015 worldwide prescription drug sales...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28642595/3d-bayesian-cluster-analysis-of-super-resolution-data-reveals-lat-recruitment-to-the-t-cell-synapse
#12
Juliette Griffié, Leigh Shlomovich, David J Williamson, Michael Shannon, Jesse Aaron, Satya Khuon, Garth L Burn, Lies Boelen, Ruby Peters, Andrew P Cope, Edward A K Cohen, Patrick Rubin-Delanchy, Dylan M Owen
Single-molecule localisation microscopy (SMLM) allows the localisation of fluorophores with a precision of 10-30 nm, revealing the cell's nanoscale architecture at the molecular level. Recently, SMLM has been extended to 3D, providing a unique insight into cellular machinery. Although cluster analysis techniques have been developed for 2D SMLM data sets, few have been applied to 3D. This lack of quantification tools can be explained by the relative novelty of imaging techniques such as interferometric photo-activated localisation microscopy (iPALM)...
June 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28642368/the-influence-of-disulfide-bonds-on-the-mechanical-stability-of-proteins-is-context-dependent
#13
Aitor Manteca, Álvaro Alonso-Caballero, Marie Fertin, Simon Poly, David De Sancho, Raul Perez-Jimenez
Disulfide bonds play a crucial role in proteins, modulating their stability and constraining their conformational dynamics. A particularly important case is that of proteins that need to withstand forces arising from their normal biological function and that are often disulfide bonded. However, the influence of disulfides on the overall mechanical stability of proteins is poorly understood. Here, we used single-molecule force spectroscopy (smFS) to study the role of disulfide bonds in different mechanical proteins in terms of their unfolding forces...
June 22, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28642366/saccharomyces-cerevisiae-red1-protein-exhibits-nonhomologous-dna-end-joining-activity-and-potentiates-hop1-promoted-pairing-of-double-stranded-dna
#14
Rucha Kshirsagar, Indrajeet Ghodke, Kalappa Muniyappa
Elucidation of the function of synaptonemal complex (SC) in <Saccharomyces cerevisiae> has mainly focused on in vivo analysis of recombination-defective meiotic mutants. Consequently, significant gaps remain in the mechanistic understanding of the activities of different SC proteins and the functional relationships among them. S. cerevisiae Hop1 and Red1 are essential structural components of the SC axial/lateral elements. Previous studies have demonstrated that Hop1 is a structure-specific DNA-binding protein that exhibits high affinity for the Holliday junction, promotes DNA bridging, condensation and pairing between duplex DNA molecules...
June 22, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28642169/a-novel-method-to-quantify-base-substitution-mutations-at-the-10-6-per-bp-level-in-dna-samples
#15
Satoshi Yamashita, Naoko Iida, Hideyuki Takeshima, Naoko Hattori, Maeda Masahiro, Takayoshi Kishino, Reiko Nagano, Taichi Shimazu, Shoichiro Tsugane, Toshikazu Ushijima
Somatic base substitution mutations of frequencies at the 10(-6)/bp level are expected to be present in many biomedical samples, such as tissues exposed to carcinogenic factors and exhausted stem cells. However, measurement of such rare mutations has been very difficult in human DNA samples. Here, we invented the use of 100 copies of genomic DNA as a template for amplicon deep sequencing so that a real mutation in a single DNA molecule would be detected at a variant allele frequency of 1% while sequencing errors have less frequency...
June 19, 2017: Cancer Letters
https://www.readbyqxmd.com/read/28642093/functional-characterization-of-3-ketosteroid-9%C3%AE-hydroxylases-in-rhodococcus-ruber-strain-chol-4
#16
Govinda Guevara, Laura Fernández de Las Heras, Julián Perera, Juana María Navarro Llorens
The 3-Ketosteroid-9α-Hydroxylase, also known as KshAB [androsta-1,4-diene-3,17-dione, NADH:oxygen oxidoreductase (9α-hydroxylating); EC 1.14.13.142)], is a key enzyme in the general scheme of the bacterial steroid catabolism in combination with a 3-ketosteroid-Δ(1)-dehydrogenase activity (KstD), being both responsible of the steroid nucleus (rings A/B) breakage. KshAB initiates the opening of the steroid ring by the 9α-hydroxylation of the C9 carbon of 4-ene-3-oxosteroids (e.g. AD) or 1,4-diene-3-oxosteroids (e...
June 19, 2017: Journal of Steroid Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28642036/transcription-factor-decoy-technology-a-therapeutic-update
#17
REVIEW
Markus Hecker, Andreas H Wagner
Targeting transcription factors represents one possibility to interfere with a known activated regulatory pathway that promotes disease. Double-stranded transcription factor decoy (TFD) oligodeoxynucleotides (ODN) are therapeutic drug candidates, which are able to specifically target and neutralize key transcription factors involved in the pathogenesis of a given disease. These short double-stranded TFD molecules mimic the consensus DNA binding site of a specific transcription factor in the promoter region of its target genes...
June 19, 2017: Biochemical Pharmacology
https://www.readbyqxmd.com/read/28641523/radiosensitizing-effect-of-electrochemotherapy-a-systematic-review-of-protocols-and-efficiency
#18
Zohre Rezaee, Ali Yadollahpour, Samaneh Rashidi, Pramod S Kunwar
OBJECTIVE: Electrochemotherapy (ECT) is a combination of electroporation (EP) and chemotherapy and has been reported as a potential radiosensitizing agent for radiation therapy. The main objective of this study was to systematically review of the literature to evaluate the effectiveness of ECT in sensitization of tumors to ionization radiation. In addition, the clinical considerations and mechanisms of action of radiosensitizing effect are discussed. METHODS: The databases of Medline (PubMed), Embase, Scopus, Cochrane library, Web of Science, Biomed central, Science Direct, and Google scholar up to March 30th 2017 were explored...
June 21, 2017: Current Drug Targets
https://www.readbyqxmd.com/read/28641521/lncrna-hotair-polymorphisms-association-with-cancer-susceptibility-in-different-tumor-types
#19
Gerardo Botti, Francesca Collina, Giosuè Scognamiglio, Gabriella Aquino, Margherita Cerrone, Giuseppina Liguori, Vincenzo Gigantino, Maria Gabriella Malzone, Monica Cantile
Single nucleotide polymorphisms (SNPs) in non coding RNAs (ncRNA) molecules affect gene and protein expression and generate genetic variability influencing the risk of tumor diseases. HOTAIR is locates at the heart of the cell memory gene program and represents a prototype of long non coding RNA (LncRNA) due to its capacity to regulate in-trans a distant chromosome landscape. Aberrant expression of HOTAIR is frequently associated with pathogenesis and mostly with metastatic progression of several human cancers...
June 21, 2017: Current Drug Targets
https://www.readbyqxmd.com/read/28641443/dissecting-the-accountability-of-parameterized-and-parameter-free-single-hybrid-and-double-hybrid-functionals-for-photophysical-properties-of-tadf-based-oleds
#20
Mojtaba Alipour, Niloofar Karimi
Organic light emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters are an attractive category of materials that have witnessed a booming development in recent years. In the present contribution, we scrutinize the accountability of parameterized and parameter-free single-hybrid (SH) and double-hybrid (DH) functionals through the two formalisms, full time-dependent density functional theory (TD-DFT) and Tamm-Dancoff approximation (TDA), for the estimation of photophysical properties like absorption energy, emission energy, zero-zero transition energy, and singlet-triplet energy splitting of TADF molecules...
June 21, 2017: Journal of Chemical Physics
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