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https://www.readbyqxmd.com/read/28441475/2-2-spirobis-chromene-derivatives-chemistry-and-their-relation-with-the-multistate-system-of-anthocyanins
#1
Artur J Moro, A Jorge Parola, Fernando Pina, Ana-Maria Pana, Valentin Badea, Iulia Pausescu, Sergiu Shova, Liliana Cseh
The chemistry of 2,2'-spirobis[chromene] derivatives is intimately related to the one of anthocyanins and similar compounds. The 2,2'-spirobis[chromene] species plays a central role in the network of chemical reactions connecting two different flavylium-based multistate systems. In the present work, a new asymmetric 2,2'-spirobis[chromene] intermediate possessing a constrained propylenic bridge between carbons 3 and 3' was isolated and its role as a pivot in the anthocyanins-type multistate of chemical reactions was investigated by the conjugation of absorption spectroscopy, stopped-flow, NMR and X-Ray crystallography...
April 25, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28441021/photophysical-and-electroluminescent-properties-of-ptag2-acetylide-complexes-supported-with-meso-and-rac-tetraphosphine
#2
Hui-Xing Shu, Jin-Yun Wang, Qian-Chong Zhang, Zhong-Ning Chen
1,2-Bis[[(diphenylphosphino)methyl](phenyl)phosphino]ethane (dpmppe) was prepared as a new tetraphosphine, and the corresponding rac and meso stereoisomers were successfully separated in view of their solubility difference in acetone. The substitution of PPh3 into Pt(PPh3)2(C≡CR)2 (R = aryl) with rac- or meso-dpmppe gives Pt(rac-dpmppe)(C≡CR)2 or Pt(meso-dpmppe)(C≡CR)2, respectively. Using Pt(rac-dpmppe)(C≡CR)2 or Pt(meso-dpmppe)(C≡CR)2 as a precursor, PtAg2 heterotrinuclear cluster complexes were synthesized and characterized by X-ray crystallography...
April 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28441011/synthesis-characterization-and-dft-analysis-of-bis-terpyridyl-based-molecular-cobalt-complexes
#3
Safwan Aroua, Tanya K Todorova, Paul Hommes, Lise-Marie Chamoreau, Hans-Ulrich Reissig, Victor Mougel, Marc Fontecave
Terpyridine ligands are widely used in chemistry and material sciences owing to their ability to form stable molecular complexes with a large variety of metal ions. In that context, variations of the substituents on the terpyridine ligand allow modulation of the material properties. Applying the Stille cross-coupling reaction, we prepared with good yields a new series of terpyridine ligands possessing quinoline-type moieties in ortho, meta, and para positions and dimethylamino substituents at central or distal positions...
April 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28440831/systematic-investigations-on-fused-%C3%AF-system-compounds-of-seven-benzene-rings-prepared-by-photocyclization-of-diphenanthrylethenes
#4
Shota Fujino, Minoru Yamaji, Hideki Okamoto, Toshiki Mutai, Isao Yoshikawa, Hirohiko Houjou, Fumito Tani
We studied the photoproducts of 1-(n-phenanthryl)-2-(m-phenanthryl)ethenes (nEm; n, m = 1, 3 and 9) for understanding photocyclization patterns based on NMR spectroscopy. The crystal structures of the photoproducts were analyzed by X-ray crystallography, and the photophysical features of the photocyclized molecules were investigated based on emission and transient absorption measurements. Phenanthrene derivatives substituted at the 1- and 3-positions were prepared for synthesizing nEm by photocyclization of stilbene derivatives...
April 25, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28440794/se-sad-serial-femtosecond-crystallography-datasets-from-selenobiotinyl-streptavidin
#5
Chun Hong Yoon, Hasan DeMirci, Raymond G Sierra, E Han Dao, Radman Ahmadi, Fulya Aksit, Andrew L Aquila, Alexander Batyuk, Halilibrahim Ciftci, Serge Guillet, Matt J Hayes, Brandon Hayes, Thomas J Lane, Meng Liang, Ulf Lundström, Jason E Koglin, Paul Mgbam, Yashas Rao, Theodore Rendahl, Evan Rodriguez, Lindsey Zhang, Soichi Wakatsuki, Sébastien Boutet, James M Holton, Mark S Hunter
We provide a detailed description of selenobiotinyl-streptavidin (Se-B SA) co-crystal datasets recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) for selenium single-wavelength anomalous diffraction (Se-SAD) structure determination. Se-B SA was chosen as the model system for its high affinity between biotin and streptavidin where the sulfur atom in the biotin molecule (C10H16N2O3S) is substituted with selenium. The dataset was collected at three different transmissions (100, 50, and 10%) using a serial sample chamber setup which allows for two sample chambers, a front chamber and a back chamber, to operate simultaneously...
April 25, 2017: Scientific Data
https://www.readbyqxmd.com/read/28439266/a-novel-regulator-of-activation-induced-cytidine-deaminase-apobecs-in-immunity-and-cancer-schr%C3%A3-dinger-s-catalytic-pocket
#6
REVIEW
Justin J King, Mani Larijani
Activation-induced cytidine deaminase (AID) and its relative APOBEC3 cytidine deaminases boost immune response by mutating immune or viral genes. Because of their genome-mutating activities, AID/APOBECs are also drivers of tumorigenesis. Due to highly charged surfaces, extensive non-specific protein-protein/nucleic acid interactions, formation of polydisperse oligomers, and general insolubility, structure elucidation of these proteins by X-ray crystallography and NMR has been challenging. Hence, almost all available AID/APOBEC structures are of mutated and/or truncated versions...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28439022/structure-of-a-protective-epitope-of-group-b-streptococcus-type-iii-capsular-polysaccharide
#7
Filippo Carboni, Roberto Adamo, Monica Fabbrini, Riccardo De Ricco, Vittorio Cattaneo, Barbara Brogioni, Daniele Veggi, Vittoria Pinto, Irene Passalacqua, Davide Oldrini, Rino Rappuoli, Enrico Malito, Immaculada Y Ros Margarit, Francesco Berti
Despite substantial progress in the prevention of group B Streptococcus (GBS) disease with the introduction of intrapartum antibiotic prophylaxis, this pathogen remains a leading cause of neonatal infection. Capsular polysaccharide conjugate vaccines have been tested in phase I/II clinical studies, showing promise for further development. Mapping of epitopes recognized by protective antibodies is crucial for understanding the mechanism of action of vaccines and for enabling antigen design. In this study, we report the structure of the epitope recognized by a monoclonal antibody with opsonophagocytic activity and representative of the protective response against type III GBS polysaccharide...
April 24, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28437446/solid-state-characterization-and-theoretical-study-of-non-linear-optical-properties-of-a-fluoro-n-acylhydrazide-derivative
#8
Rosemberg F N Rodrigues, Leonardo R Almeida, Florisberto G Dos Santos, Paulo S Carvalho, Wanderson C de Souza, Kleber S Moreira, Gilberto L B de Aquino, Clodoaldo Valverde, Hamilton B Napolitano, Basílio Baseia
In this work we determine the linear and non-linear optical properties of a Fluoro-N-Acylhydrazide derivative (FBHZ), using a combined supermolecule approach and an iterative scheme of electrostatic polarization, where the atoms of neighbouring molecules are represented by point charges. Our results for non-linear optics (NLO) are comparable to those found experimentally, suggesting that FBHZ constitutes an attractive object for future studies and for use as an interesting material for third-order NLO applications...
2017: PloS One
https://www.readbyqxmd.com/read/28436967/microtubule-minus-end-regulation-at-spindle-poles-by-an-aspm-katanin-complex
#9
Kai Jiang, Lenka Rezabkova, Shasha Hua, Qingyang Liu, Guido Capitani, A F Maarten Altelaar, Albert J R Heck, Richard A Kammerer, Michel O Steinmetz, Anna Akhmanova
ASPM (known as Asp in fly and ASPM-1 in worm) is a microcephaly-associated protein family that regulates spindle architecture, but the underlying mechanism is poorly understood. Here, we show that ASPM forms a complex with another protein linked to microcephaly, the microtubule-severing ATPase katanin. ASPM and katanin localize to spindle poles in a mutually dependent manner and regulate spindle flux. X-ray crystallography revealed that the heterodimer formed by the N- and C-terminal domains of the katanin subunits p60 and p80, respectively, binds conserved motifs in ASPM...
April 24, 2017: Nature Cell Biology
https://www.readbyqxmd.com/read/28436701/two-cytotoxic-6-7-seco-spiro-lacton-ent-kauranoids-from-isodon-rubescens
#10
Guo-Yong Luo, Rui Deng, Jing-Jie Zhang, Jiang-Hai Ye, Lu-Tai Pan
The present study was performed to investigate the chemical components of the branches and leaves of Isodon rubescens. Two 6,7-seco-spiro-lacton-ent-kauranoids were obtained. Based on the extensive spectroscopic analyses, their structures were elucidated as 6-epi-11-O-acetylangustifolin (1) and 11-O-acetylangustifolin (2), respectively. The structure of 2 was further comfirmed by X-ray crystallography analysis. MTT method was employed to evaluate their cytotoxity against human lung cancer cell lines A549 and leukemia cell lines K562...
April 24, 2017: Journal of Asian Natural Products Research
https://www.readbyqxmd.com/read/28434999/smfret-experiments-of-the-rna-polymerase-ii-transcription-initiation-complex
#11
REVIEW
Nicole Malkusch, Thilo Dörfler, Julia Nagy, Tobias Eilert, Jens Michaelis
Single-molecule fluorescence and in particular single-molecule Förster Resonance Energy Transfer (smFRET(1)) is a powerful tool to provide real-time information on the dynamic architecture of large macromolecular structures such as eukaryotic transcription initiation complexes. In contrast to other structural biology methods, not only structural details, but dynamics transitions are revealed thus closing in on the underlying molecular mechanisms. Here, we describe a comprehensive quantitative biophysical toolbox which can be used for rigorous analysis of dynamic protein-nucleic acid complexes and is applied to the study of eukaryotic transcription initiation...
April 18, 2017: Methods: a Companion to Methods in Enzymology
https://www.readbyqxmd.com/read/28434915/x-ray-crystallography-and-electron-microscopy-of-cross-and-multi-module-nonribosomal-peptide-synthetase-proteins-reveal-a-flexible-architecture
#12
Michael J Tarry, Asfarul S Haque, Khanh Huy Bui, T Martin Schmeing
Nonribosomal peptide synthetases (NRPS) are macromolecular machines that produce peptides with diverse activities. Structural information exists for domains, didomains, and even modules, but little is known about higher-order organization. We performed a multi-technique study on constructs from the dimodular NRPS DhbF. We determined a crystal structure of a cross-module construct including the adenylation (A) and peptidyl carrier protein (PCP) domains from module 1 and the condensation domain from module 2, complexed with an adenosine-vinylsulfonamide inhibitor and an MbtH-like protein (MLP)...
April 17, 2017: Structure
https://www.readbyqxmd.com/read/28434186/new-thiourea-and-1-3-thiazolidin-4-one-derivatives-effective-on-the-hiv-1-virus
#13
Anna Bielenica, Giuseppina Sanna, Silvia Madeddu, Marta Struga, Michał Jóźwiak, Anna E Kozioł, Aleksandra Sawczenko, Ilona B Materek, Alessandra Serra, Gabriele Giliberti
Thiourea derivatives have been reported to possess many biological activities, among them antiviral and antitumoral properties. As part of our continuing effort to develop new active compounds, we report the synthesis and the evaluation of new fifteen thiourea derivatives with 1,3-benzothiazol-2-yl moiety, among them a group of biologically active (1-7) also underwent cyclisation to 1,3-thiazolidin-4-ones. Molecular structure of four compounds (4, 13, 15 and 3a) was determined by an X-ray crystallography. We here report the evaluation of their cytotoxicity against human leukaemia/lymphoma- and solid tumour-derived cell lines and of their antiviral activity against HIV-1 and representatives of ssRNA and dsDNA viruses...
April 23, 2017: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/28433015/probing-the-effects-of-surface-hydrophobicity-and-tether-orientation-on-antibody-antigen-binding
#14
Derek B Bush, Thomas A Knotts
Antibody microarrays have the potential to revolutionize molecular detection for many applications, but their current use is limited by poor reliability, and efforts to change this have not yielded fruitful results. One difficulty which limits the rational engineering of next-generation devices is that little is known, at the molecular level, about the antibody-antigen binding process near solid surfaces. Atomic-level structural information is scant because typical experimental techniques (X-ray crystallography and NMR) cannot be used to image proteins bound to surfaces...
April 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28432354/structural-and-functional-analysis-of-lysozyme-after-treatment-with-dielectric-barrier-discharge-plasma-and-atmospheric-pressure-plasma-jet
#15
Sooho Choi, Pankaj Attri, Inhwan Lee, Jeongmin Oh, Ji-Hye Yun, Ji Hoon Park, Eun Ha Choi, Weontae Lee
The variation in the biological function of proteins plays an important role in plasma medicine and sterilization. Several non-thermal plasma sources with different feeding gases are used worldwide for plasma treatment, including dielectric barrier discharge (DBD) and atmospheric-pressure plasma jet (APPJ) as the most commonly used sources. Therefore, in the present work, we used both DBD and APPJ plasma sources with N2 and air as feeding gases to evaluate the effects on the structural, thermodynamic, and activity changes of enzymes...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28432302/a-bacterial-abc-transporter-enables-import-of-mammalian-host-glycosaminoglycans
#16
Sayoko Oiki, Bunzo Mikami, Yukie Maruyama, Kousaku Murata, Wataru Hashimoto
Glycosaminoglycans (GAGs), such as hyaluronan, chondroitin sulfate, and heparin, constitute mammalian extracellular matrices. The uronate and amino sugar residues in hyaluronan and chondroitin sulfate are linked by 1,3-glycoside bond, while heparin contains 1,4-glycoside bond. Some bacteria target GAGs as means of establishing colonization and/or infection, and bacterial degradation mechanisms of GAGs have been well characterized. However, little is known about the bacterial import of GAGs. Here, we show a GAG import system, comprised of a solute-binding protein (Smon0123)-dependent ATP-binding cassette (ABC) transporter, in the pathogenic Streptobacillus moniliformis...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28432121/the-lon-protease-like-domain-in-the-bacterial-reca-paralog-rada-is-required-for-dna-binding-and-repair
#17
Masao Inoue, Kenji Fukui, Yuki Fujii, Noriko Nakagawa, Takato Yano, Seiki Kuramitsu, Ryoji Masui
Homologous recombination (HR) plays an essential role in the maintenance of genome integrity. RecA/Rad51 paralogs have been recognized as an important factor of HR. Among them, only one bacterial RecA/Rad51 paralog - RadA - is involved in HR as an accessory factor of RecA recombinase. RadA has a unique Lon protease-like domain (LonC) at its C-terminus, in addition to a RecA-like ATPase domain. Unlike Lon protease, RadA's LonC domain does not show protease activity but is still essential for RadA-mediated DNA repair...
April 21, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28430420/a-thorium-chalcogenolate-series-generated-by-atom-insertion-into-thorium-carbon-bonds
#18
Nicholas S Settineri, Mary E Garner, John Arnold
A new thorium monoalkyl complex, Th(CH2SiMe3)(L3) (L = MeC(N(i)Pr)2) (2), undergoes insertion of chalcogen atoms resulting in a series of thorium chalcogenolate complexes, Th(ECH2SiMe3)(L3) (E = S, SS, Se, Te; 5-8). Complex 6 represents the first alkyl disulfide thorium species and illustrates the ability of 2 to undergo controllable, stoichiometric atom insertion. All complexes have been characterized by (1)H and (13)C NMR spectroscopy, FTIR, EA, and melting point, and in the case of 1, 2, and 4-8, X-ray crystallography...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28429156/crystallization-and-preliminary-x-ray-diffraction-analysis-of-a-mammal-inositol-1-3-4-5-6-pentakisphosphate-2-kinase
#19
Elsa Franco-Echevarría, Julia Sanz-Aparicio, Nathalie Troffer-Charlier, Arnaud Poterszman, Beatriz González
Inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IP5 2-K) is an enzyme that catalyses the formation of phytic acid (IP6) from IP5 and ATP. In mammals, IP6 is involved in multiple events such as DNA repair and mRNA edit and it is the precursor of inositol pyrophosphates, emerging compounds shown to have an essential role in apoptosis. In addition, IP5 2-K have functions in cells independently of its catalytic activity, for example in rRNA biogenesis. We pursue the structure determination of a mammal IP5 2-K by Protein Crystallography...
April 21, 2017: Protein Journal
https://www.readbyqxmd.com/read/28428974/perspective-a-toolbox-for-protein-structure-determination-in-physiological-environment-through-oriented-2d-ordered-site-specific-immobilization
#20
M Altissimo, M Kiskinova, R Mincigrucci, L Vaccari, C Guarnaccia, C Masciovecchio
Revealing the structure of complex biological macromolecules, such as proteins, is an essential step for understanding the chemical mechanisms that determine the diversity of their functions. Synchrotron based X-ray crystallography and cryo-electron microscopy have made major contributions in determining thousands of protein structures even from micro-sized crystals. They suffer from some limitations that have not been overcome, such as radiation damage, the natural inability to crystallize a number of proteins, and experimental conditions for structure determination that are incompatible with the physiological environment...
July 2017: Structural Dynamics (Melville, N.Y.)
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