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https://www.readbyqxmd.com/read/29352977/paclitaxel-inhibited-lysozyme-fibrillation-by-increasing-colloidal-stability-through-formation-of-off-pathway-oligomers
#1
Ehsan Kachooei, Faroogh Mozaffarian, Fariba Khodagholi, Payam Sedeghi, Leila Karami, Atiyeh Ghasemi, Elham Vahdat, Ali Akbar Saboury, Nader Sheibani, Ali Akbar Moosavi-Movahedi
Protein fibrillation is a challenging issue in medicine, causing many diseases, and an impediment to pharmaceutics and protein industry. Many chemicals, especially polyphenol compounds and aromatic small molecules, have been widely used as an effective strategy to combat protein fibril formation. Hence, understanding mechanisms of fibrillation inhibition and contributing forces in this process are significant. In this study, the inhibitory effect of paclitaxel on lysozyme fibrillation was investigated with respect to thermal and colloidal stability...
January 15, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29352877/valorization-of-peanut-shells-manufacture-of-bioactive-oligosaccharides
#2
Xiana Rico, Beatriz Gullón, José Luis Alonso, Juan Carlos Parajó, Remedios Yáñez
Peanut shells were subjected to non-isothermal aqueous treatments to cause the partial breakdown of hemicelluloses into soluble oligosaccharides and lignin-derived compounds with high antioxidant activity. The effects of temperature on the chemical composition of the substrate and soluble reaction products were assessed. Under selected conditions (210°C, severity=4.09), the overall amount of poly- and oligo- saccharides present in the liquid phase reached 9.8g/L. This solution was refined by consecutive stages of discontinuous diafiltration, yielding a refined product containing about 72...
March 1, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29352863/a-chitin-deacetylase-of-podospora-anserina-has-two-functional-chitin-binding-domains-and-a-unique-mode-of-action
#3
Janina Hoßbach, Franziska Bußwinkel, Andreas Kranz, Jasper Wattjes, Stefan Cord-Landwehr, Bruno M Moerschbacher
Chitosan is a structurally diverse biopolymer that is commercially derived from chitin by chemical processing, but chitin deacetylases (CDAs) potentially offer a sustainable and more controllable approach allowing the production of chitosans with tailored structures and biological activities. We investigated the CDA from Podospora anserina (PaCDA) which is closely related to Colletotrichum lindemuthianum CDA in the catalytic domain, but unique in having two chitin-binding domains. We produced recombinant PaCDA in Hansenula polymorpha for biochemical characterization and found that the catalytic domain of PaCDA is also functionally similar to C...
March 1, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29352739/determination-of-protein-oligomeric-structure-from-small-angle-x-ray-scattering
#4
REVIEW
David A Korasick, John J Tanner
Small-angle X-ray scattering (SAXS) is useful for determining the oligomeric states and quaternary structures of proteins in solution. The average molecular mass in solution can be calculated directly from a single SAXS curve collected on an arbitrary scale from a sample of unknown protein concentration, without the need for beamline calibration or protein standards. The quaternary structure in solution can be deduced by comparing the experimental SAXS curve to theoretical curves calculated from proposed models of the oligomer...
January 20, 2018: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/29351247/b-type-and-complex-a-b-type-epicatechin-trimers-isolated-from-litchi-pericarp-aqueous-extract-show-high-antioxidant-and-anticancer-activity
#5
Yihui Gong, Fang Fang, Xin Zhang, Bin Liu, Honghui Luo, Zhen Li, Xuelian Zhang, Zhaoqi Zhang, Xuequn Pang
Litchi (Litchi chinensis Sonn.) fruit is known for its rich source of phenolics. Litchi pericarp contains high levels of epicatechin that may form oligomers of various lengths. Except for several A or B type epicatechin dimers, other soluble oligomers have rarely been identified in the pericarp. Here, bioassay-guided column fractionation was applied to isolate bioactive phenolics from aqueous pericarp extract. A fraction (S3) was obtained by two rounds of Sephadex LH-20 column chromatography, and showed higher antioxidant activity and inhibition on the proliferation of human lung cancer cells (A549) than Litchi anthocyanins...
January 19, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29350885/unexpected-impact-of-esterification-on-the-antioxidant-activity-and-photo-stability-of-a-eumelanin-from-5-6-dihydroxyindole-2-carboxylic-acid
#6
Raffaella Micillo, Mariagrazia Iacomino, Marco Perfetti, Lucia Panzella, Kenzo Koike, Gerardino D'Errico, Marco d'Ischia, Alessandra Napolitano
To inquire into the role of the carboxyl group as determinant of the properties of 5,6-dihydroxyindole melanins, melanins from aerial oxidation of 5,6-dihydroxyindole (DHICA) and its methyl ester MeDHICA were comparatively tested for their antioxidant activity. MALDI MS spectrometry analysis of MeDHICA melanin provided evidence for a collection of intact oligomers. EPR analysis showed g-values almost identical and signal amplitudes (ΔB) comparable to those of DHICA melanin, but spin density was one order of magnitude higher, with a different response to pH changes...
January 19, 2018: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/29350601/brain-tissue-a%C3%AE-42-levels-are-linked-to-shunt-response-in-idiopathic-normal-pressure-hydrocephalus
#7
Sami Abu Hamdeh, Johan Virhammar, Dag Sehlin, Irina Alafuzoff, Kristina Giuliana Cesarini, Niklas Marklund
OBJECTIVE The authors conducted a study to test if the cortical brain tissue levels of soluble amyloid beta (Aβ) reflect the propensity of cortical Aβ aggregate formation and may be an additional factor predicting surgical outcome following idiopathic normal pressure hydrocephalus (iNPH) treatment. METHODS Highly selective ELISAs (enzyme-linked immunosorbent assays) were used to quantify soluble Aβ40, Aβ42, and neurotoxic Aβ oligomers/protofibrils, associated with Aβ aggregation, in cortical biopsy samples obtained in patients with iNPH (n = 20), sampled during ventriculoperitoneal (VP) shunt surgery...
January 19, 2018: Journal of Neurosurgery
https://www.readbyqxmd.com/read/29350033/impact-of-backbone-pattern-and-residue-substitution-on-helicity-in-%C3%AE-%C3%AE-%C3%AE-peptides
#8
Young-Hee Shin, Samuel H Gellman
We have evaluated the impact of changes in the chemical structure of peptidic oligomers containing α-, β-, and γ-amino acid residues (α/β/γ-peptides) on the propensities of these oligomers to adopt helical conformations in aqueous and alcoholic solutions. These studies were inspired by our previous discovery that α/β/γ-peptides containing a regular αγααβα hexad repeat adopt an α-helix-like conformation in which the β and γ residues are aligned in a stripe along one side, and the remainder of the helix surface is defined by the α residues...
January 19, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29349888/distal-amyloid-%C3%AE-protein-fragments-template-amyloid-assembly
#9
Thanh D Do, Smriti Sangwan, Natália E C de Almeida, Alexandre I Ilitchev, Maxwell Giammona, Michael R Sawaya, Steven K Buratto, David S Eisenberg, Michael T Bowers
Amyloid formation is associated with devastating diseases such as Alzheimer's, Parkinson's and Type-2 diabetes. The large amyloid deposits found in patients suffering from these diseases have remained difficult to probe by structural means. Recent NMR models also predict heterotypic interactions from distinct peptide fragments but limited evidence of heterotypic packed sheets is observed in solution. Here we characterize two segments of the protein amyloid β (Aβ) known to form fibrils in Alzheimer's disease patients...
January 19, 2018: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/29348551/designable-and-dynamic-single-walled-stiff-nanotubes-assembled-from-sequence-defined-peptoids
#10
Haibao Jin, Yan-Huai Ding, Mingming Wang, Yang Song, Zhihao Liao, Christina J Newcomb, Xuepeng Wu, Xian-Qiong Tang, Zheng Li, Yuehe Lin, Feng Yan, Tengyue Jian, Peng Mu, Chun-Long Chen
Despite recent advances in the assembly of organic nanotubes, conferral of sequence-defined engineering and dynamic response characteristics to the tubules remains a challenge. Here we report a new family of highly designable and dynamic nanotubes assembled from sequence-defined peptoids through a unique "rolling-up and closure of nanosheet" mechanism. During the assembly process, amorphous spherical particles of amphiphilic peptoid oligomers crystallize to form well-defined nanosheets before folding to form single-walled nanotubes...
January 18, 2018: Nature Communications
https://www.readbyqxmd.com/read/29348174/oligomer-formation-and-g-quadruplex-binding-by-purified-murine-rif1-protein-a-key-organizer-of-higher-order-chromatin-architecture
#11
Kenji Moriyama, Naoko Yoshizawa-Sugata, Hisao Masai
Rap1-interacting protein 1(Rif1) regulates telomere length in budding yeast. We previously reported that, in metazoans and fission yeast, Rif1 also plays pivotal roles in controlling genome-wide DNA replication timing. We proposed that Rif1 may assemble chromatin compartments that contain specific replication-timing domains by promoting chromatin loop formation. Rif1 also is involved in DNA lesion repair, restart after replication fork collapse, anti-apoptosis activities, replicative senescence, and transcriptional regulation...
January 18, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29346322/regioselective-synthesis-of-procyanidin-b6-a-4-6-condensed-catechin-dimer-by-intramolecular-condensation
#12
Yusuke Higashino, Taisuke Okamoto, Kazuki Mori, Takashi Kawasaki, Masahiro Hamada, Noriyuki Nakajima, Akiko Saito
Proanthocyanidins, also known as condensed tannins or oligomeric flavonoids, are found in many edible plants and exhibit interesting biological activities. Herein, we report a new, simple method for the stereoselective synthesis of procyanidin B6, a (+)-catechin-(4-6)-(+)-catechin dimer, by Lewis acid-catalyzed intramolecular condensation. The 5-O-t-butyldimethylsilyl (TBDMS) group of 5,7,3'4'-tetra-O-TBDMS-(+)-catechin was regioselectively removed using trifluoroacetic acid, leading to the "regio-controlled" synthesis of procyanidin B6...
January 18, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29345922/efficient-fusion-at-neutral-ph-by-human-immunodeficiency-virus-gp41-trimers-containing-the-fusion-peptide-and-transmembrane-domain
#13
Shuang Liang, Punsisi Ratnayake, Craig Keinath, Lihui Jia, Robert Wolfe, Ahinsa Ranaweera, David P Weliky
Human immunodeficiency virus (HIV) is membrane-enveloped and an initial infection step is joining/fusion of viral and cell membranes. This step is catalyzed by gp41 which is a single-pass integral viral membrane protein. The protein contains a ~170-residue ectodomain located outside the virus that is important for fusion, and includes the fusion peptide (FP), N-helix, loop, C-helix, and viral membrane-proximal external region (MPER). The virion initially has non-covalent complexes between three gp41 ectodomains and three gp120 proteins...
January 18, 2018: Biochemistry
https://www.readbyqxmd.com/read/29345905/chelate-assisted-ring-closing-metathesis-a-strategy-for-accelerated-macrocyclization-at-ambient-temperatures
#14
Carolyn S Higman, Daniel Luis do Nascimento, Benjamin J Ireland, Stephan Audörsch, Gwendolyn A Bailey, Robert McDonald, Deryn Elizabeth Fogg
Ring-closing metathesis (RCM) offers versatile catalytic routes to macrocycles, with applications ranging from perfumery to production of antiviral drugs. Unwanted oligomerization, however, is a long-standing challenge. Oligomers can be converted into the cyclic targets by catalysts that are sufficiently reactive to promote backbiting (e.g. Ru complexes of N-heterocyclic carbenes; NHCs), but catalyst decomposition limits yields and selectivity. Incorporation of a hemilabile o-dianiline (ODA) chelate into new catalysts of the form RuCl2(NHC)(ODA)(=CHPh) accelerates macrocyclization, particularly for dienes bearing polar sites capable of H-bonding: it may also inhibit catalyst decomposition during metathesis...
January 18, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29344825/the-voltage-dependent-anion-channel-vdac-of-pacific-oysters-crassostrea-gigas-is-upaccumulated-during-infection-by-the-ostreid-herpesvirus-1-oshv-1-an-indicator-of-the-warburg-effect
#15
Lizenn Delisle, Marine Fuhrmann, Claudie Quéré, Marianna Pauletto, Vianney Pichereau, Fabrice Pernet, Charlotte Corporeau
Voltage-dependent anion channel (VDAC) is a key mitochondrial protein. VDAC drives cellular energy metabolism by controlling the influx and efflux of metabolites and ions through the mitochondrial membrane, playing a role in its permeabilization. This protein exerts a pivotal role during the white spot syndrome virus (WSSV) infection in shrimp, through its involvement in a particular metabolism that plays in favor of the virus, the Warburg effect. The Warburg effect corresponds to an atypical metabolic shift toward an aerobic glycolysis that provides energy for rapid cell division and resistance to apoptosis...
January 17, 2018: Marine Biotechnology
https://www.readbyqxmd.com/read/29343504/canonical-and-non-canonical-actions-of-arabidopsis-histone-deacetylases-in-ribosomal-rna-processing
#16
Xiangsong Chen, Li Lu, Shuiming Qian, Mark Scalf, Lloyd M Smith, Xuehua Zhong
Ribosome biogenesis is a fundamental process required for all cellular activities. Histone deacetylases play critical roles in many biological processes including transcriptional repression and rDNA silencing. However, their function in pre-rRNA processing remains poorly understood. Here, we discovered a previously uncharacterized role of Arabidopsis thaliana histone deacetylase HD2C in pre-rRNA processing via both canonical and non-canonical manners. HD2C interacts with another histone deacetylase HD2B and forms homo- and/or hetero-oligomers in the nucleolus...
January 17, 2018: Plant Cell
https://www.readbyqxmd.com/read/29343430/cardiolipin-synthesizing-enzymes-form-a-complex-that-interacts-with-cardiolipin-dependent-membrane-organizing-proteins
#17
Mauro Serricchio, Adriano Vissa, Peter K Kim, Christopher M Yip, G A McQuibban
The mitochondrial glycerophospholipid cardiolipin plays important roles in mitochondrial biology. Most notably, cardiolipin directly binds to mitochondrial proteins and helps assemble and stabilize mitochondrial multi-protein complexes. Despite their importance for mitochondrial health, how the proteins involved in cardiolipin biosynthesis are organized and embedded in mitochondrial membranes has not been investigated in detail. Here we show that human PGS1 and CLS1 are constituents of large protein complexes...
January 14, 2018: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29342507/the-role-of-autophagy-in-the-degradation-of-misfolded-hla-b27-heavy-chains
#18
Fatemeh Navid, Gerlinde Layh-Schmitt, Keith A Sikora, Antony Cougnoux, Robert A Colbert
OBJECTIVE: To determine whether autophagy is involved in the degradation of misfolded HLA-B27 in experimental spondyloarthritis. METHODS: Bone marrow derived macrophages from HLA-B27 and human β2 m (hβ2 m) transgenic rats were examined with and without IFNγ and proteasome or autophagy inhibitors. Immunoprecipitation, western blotting, and immunofluorescence were used to measure HLA-B27 heavy chains and autophagy. Autophagy was induced using rapamycin. HLA-B7/hβ2 m transgenic and wild type rat macrophages were used as controls...
January 17, 2018: Arthritis & Rheumatology
https://www.readbyqxmd.com/read/29342318/optical-structural-analysis-of-individual-%C3%AE-synuclein-oligomers
#19
Juan Alberto Varela, Margarida Rodrigues, Suman De, Patrick Flagmeier, Sonia Gandhi, Christopher M Dobson, David Klenerman, Steven Lee
Small aggregates of misfolded proteins play a key role in neurodegenerative disorders. Such species are difficult to study due to the lack of methods capable of resolving these heterogeneous aggregates, which are smaller than the optical diffraction limit. We demonstrate here an all-optical fluorescence microscopy method to characterise the structure of individual protein-aggregates based on the fluorescence anisotropy of dyes such as thioflavin-T, and show that this technology is capable of studying oligomers in human biofluids such as cerebrospinal fluid...
January 17, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29342315/oxidation-of-methylalumoxane-oligomers
#20
Harmen Zijlstra, Scott Collins, Jason Scott McIndoe
The anions formed from methylalumoxane (MAO) and suitable donors (e.g. octamethyltrisiloxane) are amenable to mass spectrometric (MS) analysis. Their composition as deduced from this data allows direct insight into the chemical transformations of their neutral precursors. One such process is oxidation, which is well-known to be facile for MAO without any clear idea of what actually occurs at a molecular level. Addition of O2 to MAO results in immediate gelation, but MS analysis reveals no corresponding change to the composition of the principal oligomeric anions...
January 17, 2018: Chemistry: a European Journal
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