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https://www.readbyqxmd.com/read/29045870/exchange-of-gramicidin-between-lipid-bilayers-implications-for-the-mechanism-of-channel-formation
#1
Kevin Lum, Helgi I Ingólfsson, Roger E Koeppe, Olaf S Andersen
The canonical mechanism of gramicidin (gA) channel formation is transmembrane dimerization of nonconducting subunits that reside in opposite bilayer leaflets. The channels do not open and close; they appear and disappear due to subunit association and dissociation. Many different types of experiments support this monomer ↔ dimer mechanism. Recently, however, this mechanism was challenged, based on experiments with lipid vesicle-incorporated gA under conditions where vesicle fusion could be controlled. In these experiments, sustained channel activity was observed long after fusion had been terminated, which led to the proposal that gA single-channel current transitions result from closed-open transitions in long-lived bilayer-spanning dimers...
October 17, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29045865/cooperative-nucleotide-binding-in-hsp90-and-its-regulation-by-aha1
#2
Philipp Wortmann, Markus Götz, Thorsten Hugel
The function of the molecular chaperone Hsp90 depends on large conformational changes, the rearrangement of local motifs, and the binding and hydrolysis of ATP. The size and complexity of the Hsp90 system impedes the detailed investigation of their interplay using standard methods. To overcome this limitation, we developed a three-color single-molecule FRET assay to study the interaction of Hsp90 with a fluorescently labeled reporter nucleotide in detail. It allows us to directly observe the cooperativity between the two nucleotide binding pockets in the protein dimer...
October 17, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29045863/high-pressure-driven-reversible-dissociation-of-%C3%AE-synuclein-fibrils-reveals-structural-hierarchy
#3
Federica Piccirilli, Nicoletta Plotegher, Maria Grazia Ortore, Isabella Tessari, Marco Brucale, Francesco Spinozzi, Mariano Beltramini, Paolo Mariani, Valeria Militello, Stefano Lupi, Andrea Perucchi, Luigi Bubacco
The analysis of the α-synuclein (aS) aggregation process, which is involved in Parkinson's disease etiopathogenesis, and of the structural feature of the resulting amyloid fibrils may shed light on the relationship between the structure of aS aggregates and their toxicity. This may be considered a paradigm of the ground work needed to tackle the molecular basis of all the protein-aggregation-related diseases. With this aim, we used chemical and physical dissociation methods to explore the structural organization of wild-type aS fibrils...
October 17, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29045795/tbhp-tbai-mediated-oxidative-cascade-reaction-consisting-of-dimerization-cyclization-and-1-2-aryl-migration-metal-free-synthesis-of-pyrrolin-4-ones-and-highly-substituted-pyrroles
#4
Xiaoyuan Zhao, Yong Zhang, Jun Deng, Daisy Zhang-Negrerie, Yunfei Du
Treatment of enamino esters with TBHP (t-butylhydroperoxide) and TBAI (t-butylammonium iodide) in HFIP (hexafluoroisopropanol) was found to afford a variety of substituted pyrrolin-4-one compounds. This metal-free oxidative cascade reaction consists of key steps of coupling of two radical intermediates, intramolecular ring closure, and an exclusive 1,2-aryl radical migration. Upon treatment with base, the obtained pyrrolin-4-ones could be converted to the highly substituted pyrrole compounds.
October 18, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29045565/cigarette-sidestream-smoke-delays-nucleotide-excision-repair-inhibited-accumulation-of-repair-proteins-at-dna-lesions
#5
Guang Yang, Yuko Ibuki
Cigarette sidestream smoke (CSS) contains many carcinogens that induce DNA damage. DNA damage plays an important role in the initiation of cancer and several diseases, and repair is the major defense mechanism; however, the relationship between CSS and the repair of DNA damage remains unclear. We herein investigated whether CSS influences nucleotide excision repair (NER) in vivo and in vitro. HR-1 hairless mouse skin treated with CSS was exposed to UVB, as a result of which pyrimidine dimers (cyclobutane pyrimidine dimers (CPDs) and pyrimidine(6-4)pyrimidone photoproducts (6-4PPs)) were formed and repaired via the NER pathway...
October 13, 2017: Carcinogenesis
https://www.readbyqxmd.com/read/29045454/insights-into-the-inhibited-form-of-the-redox-sensitive-sufe-like-sulfur-acceptor-csde
#6
Esther Peña-Soler, Juan Aranda, Miguel López-Estepa, Sara Gómez, Fernando Garces, Miquel Coll, Francisco J Fernández, Iñaki Tuñon, M Cristina Vega
Sulfur trafficking in living organisms relies on transpersulfuration reactions consisting in the enzyme-catalyzed transfer of S atoms via activated persulfidic S across protein-protein interfaces. The recent elucidation of the mechanistic basis for transpersulfuration in the CsdA-CsdE model system has paved the way for a better understanding of its role under oxidative stress. Herein we present the crystal structure of the oxidized, inactivated CsdE dimer at 2.4 Å resolution. The structure sheds light into the activation of the Cys61 nucleophile on its way from a solvent-secluded position in free CsdE to a fully extended conformation in the persulfurated CsdA-CsdE complex...
2017: PloS One
https://www.readbyqxmd.com/read/29045138/importance-of-the-c-terminus-of-aldh7a1-for-oligomerization-and-catalytic-activity
#7
David Korasick, Jesse Wyatt, Min Luo, Adrian R Laciak, Kasi Ruddraraju, Kent S Gates, Michael T Henzl, John J Tanner
Aldehyde dehydrogenase 7A1 (ALDH7A1) catalyzes the terminal step of lysine catabolism, the NAD+-dependent oxidation of α-aminoadipate semialdehyde to α-aminoadipate. Structures of ALDH7A1 reveal the C-terminus is a gate that opens and closes in response to the binding of α-aminoadipate. In the closed state, the C-terminus of one protomer stabilizes the active site of the neighboring protomer in the dimer-of-dimers tetramer. Specifically, Ala505 and Gln506 interact with the conserved aldehyde-anchor-loop in the closed state...
October 18, 2017: Biochemistry
https://www.readbyqxmd.com/read/29044686/thiol-ene-clickable-gelatin-a-platform-bioink-for-multiple-3d-biofabrication-technologies
#8
Sarah Bertlein, Gabriella Brown, Khoon S Lim, Tomasz Jungst, Thomas Boeck, Torsten Blunk, Joerg Tessmar, Gary J Hooper, Tim B F Woodfield, Juergen Groll
Bioprinting can be defined as the art of combining materials and cells to fabricate designed, hierarchical 3D hybrid constructs. Suitable materials, so called bioinks, have to comply with challenging rheological processing demands and rapidly form a stable hydrogel postprinting in a cytocompatible manner. Gelatin is often adopted for this purpose, usually modified with (meth-)acryloyl functionalities for postfabrication curing by free radical photopolymerization, resulting in a hydrogel that is cross-linked via nondegradable polymer chains of uncontrolled length...
October 17, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29044295/clinical-decision-rules-for-pulmonary-embolism-in-hospitalized-patients-a-systematic-literature-review-and-meta-analysis
#9
Anne R Bass, Kara G Fields, Rie Goto, Gregory Turissini, Shirin Dey, Linda A Russell
Background Clinical decision rules (CDRs) for pulmonary embolism (PE) have been validated in outpatients, but their performance in hospitalized patients is not well characterized. Objectives The goal of this systematic literature review was to assess the performance of CDRs for PE in hospitalized patients. Methods We performed a structured literature search using Medline, EMBASE and the Cochrane library for articles published on or before January 18, 2017. Two authors reviewed all titles, abstracts and full texts...
October 10, 2017: Thrombosis and Haemostasis
https://www.readbyqxmd.com/read/29044185/structural-analysis-of-variant-of-helicobacter-pylori-motb-in-its-activated-form-engineered-as-chimera-of-motb-and-leucine-zipper
#10
Daniel A Andrews, Yuri E Nesmelov, Matthew C Wilce, Anna Roujeinikova
Rotation of the bacterial flagellum is powered by a proton influx through the peptidoglycan (PG)-tethered stator ring MotA/B. MotA and MotB form an inner-membrane complex that does not conduct protons and does not bind to PG until it is inserted into the flagellar motor. The opening of the proton channel involves association of the plug helices in the periplasmic region of the MotB dimer into a parallel coiled coil. Here, we have characterised the structure of a soluble variant of full-length Helicobacter pylori MotB in which the plug helix was engineered to be locked in a parallel coiled coil state, mimicking the open state of the stator...
October 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29044109/apobec3h-structure-reveals-an-unusual-mechanism-of-interaction-with-duplex-rna
#11
Jennifer A Bohn, Keyur Thummar, Ashley York, Alice Raymond, W Clay Brown, Paul D Bieniasz, Theodora Hatziioannou, Janet L Smith
The APOBEC3 family of cytidine deaminases cause lethal hypermutation of retroviruses via deamination of newly reverse-transcribed viral DNA. Their ability to bind RNA is essential for virion infiltration and antiviral activity, yet the mechanisms of viral RNA recognition are unknown. By screening naturally occurring, polymorphic, non-human primate APOBEC3H variants for biological and crystallization properties, we obtained a 2.24-Å crystal structure of pig-tailed macaque APOBEC3H with bound RNA. Here, we report that APOBEC3H forms a dimer around a short RNA duplex and, despite the bound RNA, has potent cytidine deaminase activity...
October 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/29044096/a-homologue-of-the-parkinson-s-disease-associated-protein-lrrk2-undergoes-a-monomer-dimer-transition-during-gtp-turnover
#12
Egon Deyaert, Lina Wauters, Giambattista Guaitoli, Albert Konijnenberg, Margaux Leemans, Susanne Terheyden, Arsen Petrovic, Rodrigo Gallardo, Laura M Nederveen-Schippers, Panagiotis S Athanasopoulos, Henderikus Pots, Peter J M Van Haastert, Frank Sobott, Christian Johannes Gloeckner, Rouslan Efremov, Arjan Kortholt, Wim Versées
Mutations in LRRK2 are a common cause of genetic Parkinson's disease (PD). LRRK2 is a multi-domain Roco protein, harbouring kinase and GTPase activity. In analogy with a bacterial homologue, LRRK2 was proposed to act as a GTPase activated by dimerization (GAD), while recent reports suggest LRRK2 to exist under a monomeric and dimeric form in vivo. It is however unknown how LRRK2 oligomerization is regulated. Here, we show that oligomerization of a homologous bacterial Roco protein depends on the nucleotide load...
October 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/29043995/clinical-research-of-homocysteine-high-sensitive-c-reactive-protein-and-d-dimer-in-patients-with-vascular-dementia
#13
Li Zhang, Na Liu, Jinying Zhang, Hui Zhang, Ying Zhang
Aim of the present research work was to study the relationship between the degree of dementia and the serum levels of homocysteine(Hcy), high-sensitive C-reactive protein(hs-CRP), D-Dimer and vascular dementia(VaD) of patients, and to investigate the mechanism of Hcy, hs-CRP and D-Dimer in the vascular dementia. Subjects were divided into normal group and VaD group. CRP and D-Dimer protein of each sample were detected by nephelometry method, and the serum Hcy level was detected by Fluorescent labeling immunoassay method...
July 2017: Pakistan Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29043850/age-adjusted-d-dimer-cut-off-in-the-diagnostic-strategy-for-deep-vein-thrombosis-a-systematic-review
#14
Mads Nybo, Anne-Mette Hvas
BACKGROUND: Studies have indicated that use of an age-adjusted D-dimer cut-off value for patients above 50 years increases utility of the diagnostic strategy for pulmonary embolism. Evidence for the same approach regarding diagnosis of deep vein thrombosis (DVT) is, however, unclear. MATERIALS AND METHODS: A systematic literature review was conducted following the PRISMA Statement guideline to gather the existing knowledge on the use of an age-adjusted D-dimer cut-off in the diagnostic strategy for DVT...
October 18, 2017: Scandinavian Journal of Clinical and Laboratory Investigation
https://www.readbyqxmd.com/read/29043798/jozilebomines-a-and-b-naphthylisoquinoline-dimers-from-the-congolese-liana-ancistrocladus-ileboensis-with-antiausterity-activities-against-the-panc-1-human-pancreatic-cancer-cell-line
#15
Jun Li, Raina Seupel, Torsten Bruhn, Doris Feineis, Marcel Kaiser, Reto Brun, Virima Mudogo, Suresh Awale, Gerhard Bringmann
Two new naphthylisoquinoline dimers, jozilebomines A (1a) and B (1b), were isolated from the roots of the Congolese plant Ancistrocladus ileboensis, along with the known dimer jozimine A2 (2). These compounds are Dioncophyllaceae-type metabolites, i.e., lacking oxygen functions at C-6 and with an R-configuration at C-3 in their tetrahydroisoquinoline moieties. The dimers 1a and 1b consist of two 7,1'-coupled naphthylisoquinoline monomers linked through an unprecedented 3',6″-coupling in the binaphthalene core and not, as in 2, via the C-3-positions of the two naphthalene units...
October 18, 2017: Journal of Natural Products
https://www.readbyqxmd.com/read/29043777/isoform-selective-atad2-chemical-probe-with-novel-chemical-structure-and-unusual-mode-of-action
#16
Amaury E Fernández-Montalván, Markus Berger, Benno Kuropka, Seong Joo Koo, Volker Badock, Joerg Weiske, Vera Puetter, Simon J Holton, Detlef Stöckigt, Antonius Ter Laak, Paolo A Centrella, Matthew A Clark, Christoph E Dumelin, Eric A Sigel, Holly H Soutter, Dawn M Troast, Ying Zhang, John W Cuozzo, Anthony D Keefe, Didier Roche, Vincent Rodeschini, Apirat Chaikuad, Laura Díaz-Sáez, James M Bennett, Oleg Fedorov, Kilian V M Huber, Jan Huebner, Hilmar Weinmann, Ingo V Hartung, Matyas Gorjanacz
ATAD2 (ANCCA) is an epigenetic regulator and transcriptional co-factor, whose over-expression has been linked to the progress of various cancer types. Here we report a DNA-encoded library screen leading to the discovery of BAY-850, a potent and isoform selective inhibitor that specifically induces ATAD2 bromodomain dimerization, and prevents interactions with acetylated histones in vitro, as well as with chromatin in cells. These features qualify BAY-850 as chemical probe to explore ATAD2 biology.
October 18, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/29043662/stryphnodendron-adstringens-barbatim%C3%A3-o-leaf-fraction-chemical-characterization-antioxidant-activity-and-cytotoxicity-towards-human-breast-cancer-cell-lines
#17
A P L Sabino, L M S Eustáquio, A C F Miranda, C Biojone, T N Mariosa, Cibele Marli Cação Paiva Gouvêa
We evaluated the chemical composition, antioxidant activity, and antitumor potential of a fraction that was isolated from Stryphnodendron adstringens (barbatimão) leaf aqueous extract. Fraction is composed by gallic acid, procyanidin dimer B1, and (-)-epicatechin-3-O-gallate and it exhibits antioxidant and cytotoxic activities. Fraction was cytotoxic against two human breast cancer cell lines, ER (+) and MCF-7 and the triple-negative, MDA-MB-435. The sulforhodamine B assay showed that, as compared to normal control cells, the fraction significantly (P < 0...
October 17, 2017: Applied Biochemistry and Biotechnology
https://www.readbyqxmd.com/read/29043336/on-verdigris-part-i-synthesis-crystal-structure-solution-and-characterisation-of-the-1-2-0-phase-cu3-ch3coo-2-oh-4
#18
Sebastian Bette, Reinhard K Kremer, Gerhard Eggert, Chiu C Tang, Robert E Dinnebier
Known synthesis approaches for basic copper(ii) acetates, the main components of historic verdrigis pigments were reinvestigated and revealed to be partially irreproducible. A modification of the reaction conditions led to the successful and reproducible synthesis of the 1-2-0 phase (Cu3(CH3COO)2(OH)4 = 1Cu(CH3COO)2·2Cu(OH)2·0H2O). The phase composition was derived from elemental and thermal analysis and confirmed by the crystal structure solution using synchrotron X-ray powder diffraction (XRPD) data. The 1-2-0 phase crystallises in space group Pbca with lattice parameters of a = 20...
October 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29043331/%C3%AE-pyridine-bridged-copper-complex-with-robust-proton-reducing-ability
#19
Karunamay Majee, Jully Patel, Babulal Das, Sumanta Kumar Padhi
The binuclear copper complex [Cu(DQPD)]2 (where DQPD = deprotonated N(2),N(6)-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (DQPDH2)) was synthesised and characterised by various spectroscopic as well as electrochemical techniques. The binuclear copper complex was converted into a mononuclear one by the addition of 2 equivalents of pTsOH into [Cu(DQPD)]2. The interconversion between the dimer and monomer complex was studied through UV-Vis spectroscopy and cyclic voltammetry. The mononuclear copper complex showed high catalytic activity towards electrochemical proton reduction using acetic acid as the external proton source in 95 : 5 (v/v) DMF/H2O...
October 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29042652/computational-analysis-of-the-molecular-mechanism-of-ramr-mutations-contributing-to-antimicrobial-resistance-in-salmonella-enterica
#20
Yen-Yi Liu, Chih-Chieh Chen
Antimicrobial resistance (AMR) in pathogenic microorganisms with multidrug resistance (MDR) constitutes a severe threat to human health. A major causative mechanism of AMR is mediated through the multidrug efflux pump (MEP). The resistance-nodulation-division superfamily (RND family) of Gram-negative bacteria is usually the major cause of MDR in clinical studies. In Salmonella enterica, the RND pump is translated from the arcAB gene, which is regulated by the activator RamA. Many MEP-caused AMR strains have high ramA gene expression due to mutations in RamR, which has a homodimeric structure comprising the dimerization domain and DNA-binding domain (DBD)...
October 17, 2017: Scientific Reports
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