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https://www.readbyqxmd.com/read/28722679/reversibility-of-a%C3%AE-oligomer-neurotoxicity
#1
EDITORIAL
Wataru Araki
No abstract text is available yet for this article.
July 7, 2017: Oncotarget
https://www.readbyqxmd.com/read/28722658/the-golgi-localized-gamma-ear-containing-arf-binding-gga-protein-family-alters-alpha-synuclein-%C3%AE-syn-oligomerization-and-secretion
#2
Bjoern von Einem, Judith Eschbach, Martin Kiechle, Anke Wahler, Dietmar R Thal, Pamela J McLean, Jochen H Weishaupt, Albert C Ludolph, Christine A F von Arnim, Karin M Danzer
Several age-related neurodegenerative disorders are associated with protein misfolding and aggregation of toxic peptides. α-synuclein (α-syn) aggregation and the resulting cytotoxicity is a hallmark of Parkinson's disease (PD) as well as dementia with Lewy bodies. Rising evidence points to oligomeric and pre-fibrillar forms as the pathogenic species, and oligomer secretion seems to be crucial for the spreading and progression of PD pathology. Recent studies implicate that dysfunctions in endolysosomal/autophagosomal pathways increase α-syn secretion...
July 15, 2017: Aging
https://www.readbyqxmd.com/read/28722655/key-steps-in-unconventional-secretion-of-fibroblast-growth-factor-2-reconstituted-with-purified-components
#3
Julia P Steringer, Sascha Lange, Sabína Čujová, Radek Šachl, Chetan Poojari, Fabio Lolicato, Oliver Beutel, Hans-Michael Müller, Sebastian Unger, Ünal Coskun, Alf Honigmann, Ilpo Vattulainen, Martin Hof, Christian Freund, Walter Nickel
FGF2 is secreted from cells by an unconventional secretory pathway. This process is mediated by direct translocation across the plasma membrane. Here, we define the minimal molecular machinery required for FGF2 membrane translocation in a fully reconstituted inside-out vesicle system. FGF2 membrane translocation is thermodynamically driven by PI(4,5)P2-induced membrane insertion of FGF2 oligomers. The latter serve as dynamic translocation intermediates of FGF2 with a subunit number in the range of 8-12 FGF2 molecules...
July 19, 2017: ELife
https://www.readbyqxmd.com/read/28722343/free-standing-photonic-glasses-fabricated-in-a-centrifugal-field
#4
Mengdi Chen, Danja Fischli, Lukas Schertel, Geoffroy J Aubry, Benedikt Häusele, Sebastian Polarz, Georg Maret, Helmut Cölfen
One efficient method to obtain disordered colloidal packing is to reduce the stability of colloidal particles by adding electrolytes to the colloidal dispersions. But the correct amount of additional electrolytes must be found empirically. Here, the effect of CaCl2 on polystyrene colloidal dispersions is studied, and a link between the amount of CaCl2 and the corresponding glassy colloidal structure is quantitatively built. A threshold concentration of CaCl2 is found by dynamic light scattering. When exceeding this threshold, different nanoparticle oligomers are observed in the dispersions by analytical ultracentrifugation...
July 19, 2017: Small
https://www.readbyqxmd.com/read/28720894/coronavirus-nucleocapsid-proteins-assemble-constitutively-in-high-molecular-oligomers
#5
Yingying Cong, Franziska Kriegenburg, Cornelis A M de Haan, Fulvio Reggiori
Coronaviruses (CoV) are enveloped viruses and rely on their nucleocapsid N protein to incorporate the positive-stranded genomic RNA into the virions. CoV N proteins form oligomers but the mechanism and relevance underlying their multimerization remain to be fully understood. Using in vitro pull-down experiments and density glycerol gradients, we found that at least 3 regions distributed over its entire length mediate the self-interaction of mouse hepatitis virus (MHV) and severe acute respiratory syndrome coronavirus (SARS-CoV) N protein...
July 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28720893/nanoplasmonic-fiber-tip-probe-detects-significant-reduction-of-intracellular-alzheimer-s-disease-related-oligomers-by-curcumin
#6
Feng Liang, Yu Wan, Diane Schaak, Joseph Ward, Xunuo Shen, Rudolph E Tanzi, Can Zhang, Qimin Quan
Considerable evidence shows critical roles of intracellular pathogenic events of Alzheimer's disease (AD). In particular, intracellular amyloid-β accumulation and oligomerization are early AD pathologic processes, which may lead to changes in inflammatory molecules and other AD-related pathological components. Curcumin and its analogs have been identified as potential drug candidates for AD. However, the effects of curcumin on intracellular AD pathologic processes remain largely unknown. Here we utilized a recently developed nanoplasmonic fiber tip probe (nFTP) technology and investigated whether curcumin leads to intracellular AD pathologic changes...
July 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28719741/macroscopic-strain-induced-transition-from-quasi-infinite-gold-nanoparticle-chains-to-defined-plasmonic-oligomers
#7
Anja Maria Steiner, Martin Mayer, Maximilian Seuss, Svetoslav Nikolov, Kenneth D Harris, Alexander Alexeev, Christian Kuttner, Tobias A F Koenig, Andreas Fery
We investigate the formation of chains of few plasmonic nanoparticles - so called plasmonic oligomers - by strain induced fragmentation of linear particle assemblies. Detailed investigations of the fragmentation process are conducted by in-situ atomic force microscopy (AFM) and UV-vis-NIR spectroscopy. Based on these experimental results and mechanical simulations computed by the lattice spring model (LSM), we propose a formation mechanism which explains the observed decrease of chain polydispersity upon increasing strain and provides experimental guidelines for tailoring chain length distribution...
July 18, 2017: ACS Nano
https://www.readbyqxmd.com/read/28719200/cis-pinonic-acid-oxidation-by-hydroxyl-radicals-in-the-aqueous-phase-under-acidic-and-basic-conditions-kinetics-and-mechanism
#8
Bartlomiej Witkowski, Tomasz Gierczak
Aqueous-phase oxidation of cis-pinonic acid (CPA) by hydroxyl radicals (OH) was studied using a relative rate technique under acidic and basic conditions. Liquid chromatography (LC) coupled to the negative electrospray ionization (ESI) quadrupole tandem mass spectrometry (MS/MS) was used to monitor a disappearance of CPA and reference compounds. The measured second order reaction rate coefficients of CPA with OH were: 3.6 ± 0.3 × 10(9) M(-1)s(-1) (pH=2) and 3.0 ± 0.3 × 10(9) M(-1)s(-1) (pH = 10) - combined uncertainties are 2σ...
July 18, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28719194/molecular-modeling-of-the-major-dna-adduct-formed-from-the-food-mutagen-ochratoxin-a-in-nari-2-base-deletion-duplexes-impact-of-sequence-context-and-adduct-ionization-on-conformational-preference-and-mutagenicity
#9
Preetleen Kathuria, Purshotam Sharma, Richard A Manderville, Stacey D Wetmore
Exposure to ochratoxin A (OTA), a possible human carcinogen, leads to many different DNA mutations. As a first step toward understanding the structural basis of OTA-induced mutagenicity, the present work uses a robust computational approach and a slipped mutagenic intermediate model previously studied for C(8)-dG aromatic amine adducts to analyze the conformational features of post-replication 2-base deletion DNA duplexes containing OT-dG, the major OTA lesion at the C(8) position of guanine. Specifically, a total of 960 ns of molecular dynamics simulations (excluding trial simulations) were carried out on four OT-dG ionization states in three sequence contexts within oligomers containing the NarI recognition sequence, a known hotspot for deletion mutations induced by related adducts formed from known carcinogens...
July 18, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28717992/melting-of-polymeric-dna-double-helix-at-elevated-temperature-a-molecular-dynamics-approach
#10
Sangeeta Kundu, Sanchita Mukherjee, Dhananjay Bhattacharyya
Genomic DNA of higher organisms exists as extremely long polymers, while in bacteria and other lower organisms it is circular with no terminal base pairs. Temperature-induced melting of the DNA double helix by localized strand separation has been unattainable by molecular dynamic simulations due to more rapid fraying of the terminal base pairs in oligomeric DNA. However, local-sequence-dependent unfolding of the DNA double helix is extremely important for understanding various biochemical phenomena, and can be addressed by simulating a model polymeric DNA duplex...
August 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/28716425/characterization-and-quantification-of-flavonoids-and-organic-acids-over-fruit-development-in-american-cranberry-vaccinium-macrocarpon-cultivars-using-hplc-and-apci-ms-ms
#11
Yifei Wang, Jennifer Johnson-Cicalese, Ajay P Singh, Nicholi Vorsa
Cranberry flavonoids, including anthocyanins, flavonol glycosides and proanthocyanidins, and organic acids were characterized and quantified by HPLC and LC-MS/MS during fruit development and ripening in eight cranberry cultivars. Anthocyanin biosynthesis initiated at early fruit development and reached highest level in mature fruit, with significant differences between cultivars. Major flavonol glycosides, including the most abundant quercetin-3-galactoside and myricetin-3-galactoside, showed consistent concentrations during the season with moderate fluctuation, and were at similar levels in mature fruits of the eight cultivars...
September 2017: Plant Science: An International Journal of Experimental Plant Biology
https://www.readbyqxmd.com/read/28716076/klf8-regulates-left-right-asymmetric-patterning-through-modulation-of-kupffer-s-vesicle-morphogenesis-and-spaw-expression
#12
Che-Yi Lin, Ming-Yuan Tsai, Yu-Hsiu Liu, Yu-Fen Lu, Yi-Chung Chen, Yun-Ren Lai, Hsin-Chi Liao, Huang-Wei Lien, Chung-Hsiang Yang, Chang-Jen Huang, Sheng-Ping L Hwang
BACKGROUND: Although vertebrates are bilaterally symmetric organisms, their internal organs are distributed asymmetrically along a left-right axis. Disruption of left-right axis asymmetric patterning often occurs in human genetic disorders. In zebrafish embryos, Kupffer's vesicle, like the mouse node, breaks symmetry by inducing asymmetric expression of the Nodal-related gene, spaw, in the left lateral plate mesoderm (LPM). Spaw then stimulates transcription of itself and downstream genes, including lft1, lft2, and pitx2, specifically in the left side of the diencephalon, heart and LPM...
July 17, 2017: Journal of Biomedical Science
https://www.readbyqxmd.com/read/28714684/the-surface-of-protein-%C3%AE-6-85-can-act-as-a-template-for-recurring-peg-structure
#13
Shu-Han Chao, Jan Schaefer, Martin Gruebele
PEGylated proteins play an increasingly important role in pharmaceutical drug delivery. We recently showed that short PEG chains can affect protein structure, even when they are not making extensive contact with the protein surface. In contrast, PEG is generally assumed to form a relatively unstructured coil, whose compactness depends on solvent conditions. Here we test whether a host protein could allow PEG to form recurrent structural motifs while the PEG chain is in contact with the protein surface. We link a PEG oligomer (n=45) to one of two nearly opposite locations on the small alpha-helical protein 6-85 to investigate this question...
July 17, 2017: Biochemistry
https://www.readbyqxmd.com/read/28714592/optimized-solid-phase-assisted-synthesis-of-oleic-acid-containing-sirna-nanocarriers
#14
Sören Reinhard, Wei Zhang, Ernst Wagner
Cationic lipo-oligomers containing unsaturated oleic acid are potent siRNA carriers based on electrostatic and hydrophobic lipo-polyplex formation and endosomal membrane destabilization. Lipo-oligomers can be produced by solid-phase supported synthesis in sequence-defined form. However, the trifluoroacetic acid (TFA)-mediated removal of acid-labile protecting groups and cleavage from the resin can be accompanied by side products caused by addition of TFA to the double bonds of oleic acid. Under aqueous conditions, these TFA adducts of oleic acid are converted into hydroxystearic acid derivatives...
July 17, 2017: ChemMedChem
https://www.readbyqxmd.com/read/28714453/preparation-of-nitrogen-and-sulfur-co-doped-ordered-mesoporous-carbon-for-enhanced-microwave-absorption-performance
#15
Xiaoyan Yuan, Xingkun Xue, Hailong Ma, Shouwu Guo, Laifei Cheng
Ordered mesoporous carbon nanomaterials (OMCs) co-doped with homogeneous nitrogen and sulfur heteroatoms were prepared by nanocasting with the pyrrole oligomer catalyzed by sulfuric acid as a precursor and ordered mesoporous silica SBA-15 as a hard-template. By multi-technique approach utilization, it was demonstrated that the N and S co-doped OMCs possessed high ordered mesoporous structures, large surface areas and homogeneous distribution of heteroatoms. As an microwave absorber, the as-prepared materials exhibited a minimum reflection loss (RL) of -32...
July 17, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28713240/the-coordinated-action-of-calcineurin-and-cathepsin-d-protects-against-%C3%AE-synuclein-toxicity
#16
Andreas Aufschnaiter, Lukas Habernig, Verena Kohler, Jutta Diessl, Didac Carmona-Gutierrez, Tobias Eisenberg, Walter Keller, Sabrina Büttner
The degeneration of dopaminergic neurons during Parkinson's disease (PD) is intimately linked to malfunction of α-synuclein (αSyn), the main component of the proteinaceous intracellular inclusions characteristic for this pathology. The cytotoxicity of αSyn has been attributed to disturbances in several biological processes conserved from yeast to humans, including Ca(2+) homeostasis, general lysosomal function and autophagy. However, the precise sequence of events that eventually results in cell death remains unclear...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28712810/conformational-heterogeneity-in-the-activation-mechanism-of-bax
#17
C Ashley Barnes, Pushpa Mishra, James L Baber, Marie-Paule Strub, Nico Tjandra
Bax is known for its pro-apoptotic role within the mitochondrial pathway of apoptosis. However, the mechanism for transitioning Bax from cytosolic to membrane-bound oligomer remains elusive. Previous nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) studies defined monomeric Bax as conformationally homogeneous. Yet it has recently been proposed that monomeric Bax exists in equilibrium with a minor state that is distinctly different from its NMR structure. Here, we revisited the structural analysis of Bax using methods uniquely suited for unveiling "invisible" states of proteins, namely, NMR paramagnetic relaxation enhancements and EPR double electron-electron resonance (DEER)...
July 3, 2017: Structure
https://www.readbyqxmd.com/read/28712293/spectroscopic-study-of-thiophene-pyrrole-containing-s-n-heteroheptacenes-with-comparison-to-acenes-and-phenacenes
#18
Alexander Rudnick, Christoph Wetzel, Steffen Tscheuschner, Holger Schmalz, Astrid Vogt, Andreas Greiner, Heinz Baessler, Elena Mena-Osteritz, Peter Bäuerle, Anna Köhler
We report a detailed spectroscopic study concerning the energy levels and vibrational structure of thiophene-pyrrole containing S,N-heteroacenes. The aim of the study is first, to understand the differences in the photoluminescence (PL) efficiencies in this structurally similar series, and second, to compare the electronic structure of S,N-heteroacenes to that of linear acenes and of phenancenes, with a view to derive guidelines for the design of singlet fission material. For S,N-heteroacenes comprising seven fused heterocyclic rings, we observe a higher PL quantum yield for derivatives with terminal thienothiophene units than for thienopyrrole-capped ones...
July 16, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28712287/observation-and-simulation-of-the-transient-anion-oligomers-liclo4-n-n-1-4-in-diethyl-carbonate-liclo4-solutions
#19
Furong Wang, Pascal Pernot, Pierre Archirel, Daniel Ortiz, Sophie Le Caer, Mehran Mostafavi
NMR measurements show that diethyl carbonate (DEC, a solvent with a low dielectric constant) solutions of LiClO4 contain (LiClO4)n oligomers. The reduction of these species by solvated electrons and pre-solvated electrons is followed by picosecond pulse radiolysis measurements. The data analysis shows that several anions absorbing in the NIR and visible range are formed after the 7 ps electron pulse. In contrast with THF solutions of LiClO4, the anionic monomer (LiClO4)- is not observed in DEC solutions. This is due to the fact that DEC is a non-polar solvent favoring the clustering of the monomers in the non-irradiated solution as shown by NMR results, and also due to the instability of the anionic monomer...
July 15, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28712284/mn-ii-oxidation-by-the-multicopper-oxidase-complex-mnx-a-binuclear-activation-mechanism
#20
Alexandra V Soldatova, Lizhi Tao, Christine A Romano, Troy A Stich, William H Casey, R David Britt, Bradley M Tebo, Thomas G Spiro
The bacterial protein complex Mnx contains a multicopper oxidase (MCO) MnxG that, unusually, catalyzes the two-electron oxidation of Mn(II) to MnO2 biomineral, via a Mn(III) intermediate. Although Mn(III)/Mn(II) and Mn(IV)/Mn(III) reduction potentials are expected to be high, we find a low reduction potential, 0.38V (pH 7.8), for the MnxG type 1 Cu(2+), the electron acceptor. Indeed the type 1 Cu(2+) is not reduced by Mn(II) in the absence of molecular oxygen, indicating that substrate oxidation requires an activation step...
July 17, 2017: Journal of the American Chemical Society
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