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https://www.readbyqxmd.com/read/28821077/building-a-fructan-lc-ms-2-library-and-its-application-to-reveal-the-fine-structure-of-cereal-grain-fructans
#1
Joran Verspreet, Anders Holmgaard Hansen, Scott J Harrison, Rudy Vergauwen, Wim Van den Ende, Christophe M Courtin
A liquid chromatography-mass spectrometry (LC-MS) library is presented containing the relative retention times of 28 fructan oligomers and MS(2) spectra of 18 of them. It includes the main representatives of all fructan classes occurring in nature and with a degree of polymerization between three and five. This library enables a rapid and unambiguous detection of these 18 fructan structures in any type of sample without the need for fructan purification or the synthesis of fructan standards. Its wide applicability is demonstrated by the analysis of fructans in a set of cereal flour samples...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821008/trans-caryophyllene-inhibits-amyloid-%C3%AE-a%C3%AE-oligomer-induced-neuroinflammation-in-bv-2-microglial-cells
#2
Yawei Hu, Ziling Zeng, Baojie Wang, Shougang Guo
Amyloid β (Aβ) is the major component of senile plaques (SP) in the brains of Alzheimer's disease (AD) patients, and serves as an inflammatory stimulus for microglia. Trans-caryophyllene (TC), a major component in the essential oils derived from various species of medicinal plants, has displayed its neuro-protective effects in previous studies. However, whether TC has a protective role in AD remains unknown. In this study, the effects of TC on Aβ1-42-induced neuro-inflammation were investigated. We found that TC reduced the release of LDH in BV-2 microglial cells treated with Aβ1-42...
August 15, 2017: International Immunopharmacology
https://www.readbyqxmd.com/read/28820900/secy-seca-fusion-protein-retains-the-ability-to-mediate-protein-transport
#3
Yasunori Sugano, Arata Furukawa, Osamu Nureki, Yoshiki Tanaka, Tomoya Tsukazaki
In bacteria, the membrane protein complex SecY/E/G and SecA ATPase are essential for protein translocation. About 30% of newly synthesized proteins in the cytosol are targeted to and translocated across the cytoplasmic membrane by the Sec factors. Although a number of single-molecule analyses and structural studies, including the crystal structure of SecYEG complexed with SecA, have been published, the underlying molecular mechanisms and the functional oligomer states remain elusive. In this study, we constructed a fusion protein SecY-SecA, which induces the formation of the SecY-A/SecE/SecG complex (SecYAEG), to enable investigation of the molecular mechanisms by advanced single-molecule analyses...
2017: PloS One
https://www.readbyqxmd.com/read/28820537/syn-bn-heteroacene-cored-conjugated-oligomers-with-finely-tuned-blue-violet-luminescent-properties
#4
Wanzheng Zhang, Yubin Fu, Peirong Qiang, Jens Hunger, Shuai Bi, Wenbei Zhang, Fan Zhang
Initiated by the effective dibromination of syn-BN-heteroacenes, a series of BN-containing conjugated oligomers was successfully synthesized upon transition-metal-catalyzed cross coupling. Their electronic structures can be finely tailored through varying the fused backbone or terminal substituents, endowing them with tunable luminescent properties within blue-violet regions.
August 18, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28819074/-molecular-pathogenesis-of-polyglutamine-diseases
#5
Yuji Takahashi
Polyglutamine diseases result from gain-of-function mutations. The expanded polyglutamine tracts lead to conformational changes in proteins, resulting in their aggregation. The intermediates including monomers or oligomers, are more toxic than the aggregates to neurons. At the molecular level, protein misfolding, transcriptional dysregulation, deranged calcium homeostasis, impaired cytoskeleton/axonal transport, mitochondrial dysfunction, and RNA toxicity contribute to disease progression. Understanding the underlying pathogenesis facilitates development of therapy for polyglutamine diseases...
August 2017: Brain and Nerve, Shinkei Kenkyū No Shinpo
https://www.readbyqxmd.com/read/28818653/robust-and-thermal-healing-superhydrophobic-surfaces-by-spin-coating-of-polydimethylsiloxane
#6
Mengying Long, Shan Peng, Wanshun Deng, Xiaojun Yang, Kai Miao, Ni Wen, Xinrui Miao, Wenli Deng
HYPOTHESIS: Superhydrophobic surfaces easily lose their excellent water-repellency after damages, which limit their broad applications in practice. Thus, the fabrication of superhydrophobic surfaces with excellent durability and thermal healing should be taken into consideration. EXPERIMENTS: In this work, robust superhydrophobic surfaces with thermal healing were successfully fabricated by spin-coating method. To achieve superhydrophobicity, cost-less and fluoride-free polydimethylsiloxane (PDMS) was spin-coated on rough aluminum substrates...
August 10, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28818426/investigation-of-the-escherichia-coli-membrane-transporters-involved-in-the-secretion-of-d-lactate-based-oligomers-by-loss-of-function-screening
#7
Camila Utsunomia, Chiaki Hori, Ken'ichiro Matsumoto, Seiichi Taguchi
d-Lactate (LA)-based oligomers (D-LAOs) are unusual oligoesters consisting of d-LA and d-3-hydroxybutyrate that are produced and secreted by engineered Escherichia coli grown on glucose. The cells heterologously express LA-polymerizing polyhydroxyalkanoate synthase and monomer-supplying enzymes. In this study, we attempted to identify the D-LAO secretion route in E. coli, which is thought to be mediated by intrinsic membrane proteins. To this end, a loss-of-function screening of D-LAO secretion was carried out using 209 single-gene membrane protein deletants, which are involved in the transport of organic compounds...
August 14, 2017: Journal of Bioscience and Bioengineering
https://www.readbyqxmd.com/read/28818091/non-canonical-soluble-amyloid-beta-aggregates-and-plaque-buffering-controversies-and-future-directions-for-target-discovery-in-alzheimer-s-disease
#8
REVIEW
David L Brody, Hao Jiang, Norelle Wildburger, Thomas J Esparza
The specific amyloid-beta (Aβ) species or other amyloid-precursor protein cleavage products that are most directly related to human neurodegeneration and clinical dementia of the Alzheimer's type have not yet been directly identified. Without a clear understanding of the most relevant species, it is difficult to determine whether therapeutic candidates successfully engaged the correct target(s). Here, we review some of the controversies regarding soluble Aβ aggregates (also termed oligomers, dimers, trimers, Aβ*56, amylospheroids, etc...
August 17, 2017: Alzheimer's Research & Therapy
https://www.readbyqxmd.com/read/28817283/the-effects-of-a21g-mutation-on-transmembrane-amyloid-beta-11-40-trimer-an-in-silico-study
#9
Son Tung Ngo, Minh Tung Nguyen, Nguyen Thanh Nguyen, Van V Vu
Familial Alzheimer's disease (FAD) is passed down in family, which account for 2-3% of about 40 million AD cases worldwide. The Flemish (A21G) mutant of amyloid β (Aβ) exhibits unique properties among all hereditary mutants of FAD, including lowest aggregation rate. Recent studies showed that Aβ oligomers play key role in Alzheimer's disease (AD) pathogenesis. They could insert themselves in brain cell membrane, disrupting the membrane integrity and ion homeostasis. However, experimental studies of transmembrane Aβ oligomers have been limited due to their intrinsic heterogeneity...
August 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28816012/periodic-mesoporous-organosilica-films-with-a-tunable-steady-state-mesophase
#10
Murad A Redzheb, Sigrid Bernstorff, Barbara Sartori, Pascal Van Der Voort, Silvia Armini
The mesophase formation in spin-coated periodic mesoporous organosilica (PMO) films aged at a controlled ambient humidity is investigated by time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). The investigation demonstrates the existence of a tunable steady state in PMO spin-coated films. Thus, a film deposited at a relative humidity of 20 % has a lamellar mesophase, whereas a subsequent increase to 70 % leads to a phase transformation resulting in a P63 /mmc space group. On the other hand, an increase of the surfactant to organosilica molar ratio of between 0...
August 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28814508/dynamic-functional-assembly-of-the-torsin-aaa-atpase-and-its-modulation-by-lap1
#11
Anna R Chase, Ethan Laudermilch, Jimin Wang, Hideki Shigematsu, Takeshi Yokoyama, Christian Schlieker
TorsinA is an essential AAA+ ATPase requiring LAP1 or LULL1 as cofactors. The dynamics of the Torsin/cofactor system remain poorly understood, with previous models invoking Torsin/cofactor assemblies with fixed stoichiometries. Here, we demonstrate that TorsinA assembles into homotypic oligomers in the presence of ATP. Torsin variants mutated at the 'back' interface disrupt homo-oligomerization but still show robust ATPase activity in the presence of its cofactors. These Torsin mutants are severely compromised in their ability to rescue nuclear envelope defects in Torsin-deficient cells, suggesting that TorsinA homo-oligomers play a key role in vivo Engagement of the oligomer by LAP1 triggers ATP hydrolysis and rapid complex disassembly...
August 16, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28812751/hydrogen-bonded-rosettes-comprising-%C3%AF-conjugated-systems-as-building-blocks-for-functional-one-dimensional-assemblies
#12
Bimalendu Adhikari, Xu Lin, Mitsuaki Yamauchi, Hayato Ouchi, Keisuke Aratsu, Shiki Yagai
Hydrogen-bonded supermacrocycles (rosettes) are attractive disk-shaped noncovalent synthons for extended functional columnar nanoassemblies. They can serve not only as noncovalent monomer units for supramolecular polymers and discrete oligomers in a dilute solution but also as constituent entities for soft matters such as gels and lyotropic/thermotropic liquid crystals. However, what are the merits of using supramolecular rosettes instead of using expanded π-conjugated covalent molecules? This review covers the self-assembly of photochemically and electrochemically active π-conjugated molecules through the formation of supramolecular rosettes via directional complementary multiple hydrogen-bonding interactions...
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28812278/monomer-dependent-secondary-nucleation-in-amyloid-formation
#13
REVIEW
Sara Linse
Secondary nucleation of monomers on the surface of an already existing aggregate that is formed from the same kind of monomers may lead to autocatalytic amplification of a self-assembly process. Such monomer-dependent secondary nucleation occurs during the crystallization of small molecules or proteins and self-assembled materials, as well as in protein self-assembly into fibrous structures. Indications of secondary nucleation may come from analyses of kinetic experiments starting from pure monomers or monomers supplemented with a low concentration of pre-formed aggregates (seeds)...
August 15, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28811659/identification-synthesis-and-biological-activity-of-alkyl-guanidine-oligomers-as-potent-antibacterial-agents
#14
C Zamperini, G Maccari, D Deodato, C Pasero, I D'Agostino, F Orofino, F De Luca, E Dreassi, J D Docquier, M Botta
In the last two decades, the repertoire of clinically effective antibacterials is shrinking due to the rapidly increasing of multi-drug-resistant pathogenic bacteria. New chemical classes with innovative mode of action are required to prevent a return to the pre-antibiotic era. We have recently reported the identification of a series of linear guanidine derivatives and their antibacterial properties. A batch of a promising candidate for optimization studies (compound 1) turned out to be a mixture containing two unknown species with a better biological activity than the pure compound...
August 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28811318/the-%C3%AE-cell-assassin-iapp-cytotoxicity
#15
Daniel Raleigh, Xiaoxue Zhang, Benoit Hastoy, Anne Clark
Islet amyloid polypeptide (IAPP) forms cytotoxic oligomers and amyloid fibrils in islets in Type 2 diabetes (T2DM). The causal factors for amyloid formation are largely unknown. Mechanisms of molecular folding and assembly of human IAPP (hIAPP) into β-sheets, oligomers and fibrils have been assessed by detailed biophysical studies of hIAPP and non-fibrillogenic, rodent IAPP (rIAPP); cytotoxicity is associated with the early phases (oligomers/multimers) of fibrillogenesis. Interaction with synthetic membranes promotes β-sheet assembly possibly via a transient α-helical molecular conformation...
August 15, 2017: Journal of Molecular Endocrinology
https://www.readbyqxmd.com/read/28809559/on-the-influence-of-the-bridge-on-triplet-state-delocalization-in-linear-porphyrin-oligomers
#16
Sabine Richert, Bart Limburg, Harry L Anderson, Christiane R Timmel
The extent of triplet state delocalization is investigated in rigid linear zinc porphyrin oligomers as a function of interporphyrin bonding characteristics, specifically in meso-meso singly linked and β,meso,β fused structures, using electron paramagnetic resonance techniques. The results are compared with those of earlier measurements on porphyrin oligomers with alkyne linkers exhibiting different preferred conformations. It is shown that dihedral angles near 90° between the porphyrin planes in directly meso-to-meso linked porphyrin oligomers lead to localization of the photoexcited triplet state on a single porphyrin unit, whereas previous work demonstrated even delocalization over two units in meso-to-meso ethyne or butadiyne-bridged oligomers, where the preferred dihedral angles amount to roughly 30° and 0°, respectively...
August 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28807329/impact-of-thio-urethane-additive-and-filler-type-on-light-transmission-and-depth-of-polymerization-of-dental-composites
#17
André Luis Faria-E-Silva, Carmem Silvia Pfeifer
OBJECTIVE: This study evaluated the effects of filler type and the addition of thio-urethane oligomers on light-transmission, polymerization kinetics and depth of cure of resin composites. METHODS: BisGMA:UDMA:TEGMA (5:3:2wt%) were mixed with 0 (control) or 20wt% thio-urethane. Fillers with various sizes and refractive indices were included and refractive index (RI) measured. Unfilled resins were used as controls. The RIs of materials were measured before and after polymerization...
August 11, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28806762/a-becn1-mutation-mediates-hyperactive-autophagic-sequestration-of-amyloid-oligomers-and-improved-cognition-in-alzheimer-s-disease
#18
Altea Rocchi, Soh Yamamoto, Tabitha Ting, Yuying Fan, Katherine Sadleir, Yigang Wang, Weiran Zhang, Sui Huang, Beth Levine, Robert Vassar, Congcong He
Impairment of the autophagy pathway has been observed during the pathogenesis of Alzheimer's disease (AD), a neurodegenerative disorder characterized by abnormal deposition of extracellular and intracellular amyloid β (Aβ) peptides. Yet the role of autophagy in Aβ production and AD progression is complex. To study whether increased basal autophagy plays a beneficial role in Aβ clearance and cognitive improvement, we developed a novel genetic model to hyperactivate autophagy in vivo. We found that knock-in of a point mutation F121A in the essential autophagy gene Beclin 1/Becn1 in mice significantly reduces the interaction of BECN1 with its inhibitor BCL2, and thus leads to constitutively active autophagy even under non-autophagy-inducing conditions in multiple tissues, including brain...
August 14, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28803412/alpha-synuclein-oligomers-a-new-hope
#19
REVIEW
Nora Bengoa-Vergniory, Rosalind F Roberts, Richard Wade-Martins, Javier Alegre-Abarrategui
Alpha-synuclein is a protein implicated in Parkinson's disease and thought to be one of the main pathological drivers in the disease, although it remains unclear how this protein elicits its neurotoxic effects. Recent findings indicate that the assembly of toxic oligomeric species of alpha-synuclein may be one of the key processes for the pathology and spread of the disease. The absence of a sensitive in situ detection method has hindered the study of these oligomeric species and the role they play in the human brain until recently...
August 12, 2017: Acta Neuropathologica
https://www.readbyqxmd.com/read/28802270/intra-molecular-salt-bridge-in-bacillus-thuringiensis-cry4ba-toxin-is-involved-in-the-stability-of-helix-%C3%AE-3-that-is-needed-for-oligomerization-and-insecticidal-activity
#20
Sabino Pacheco, Isabel Gómez, Jorge Sanchez, Blanca-Ines García-Gómez, Mario Soberón, Alejandra Bravo
Bacillus thuringiensis three domain Cry toxins kill insects by forming pores in the apical membrane of larval midgut cells. Oligomerization of the toxin is an important step for pore formation. Domain I helix α-3 participates in toxin oligomerization. Here we identify an intra-molecular salt bridge within helix α-3 of Cry4Ba (D111-K115) that is conserved in many members of the family of the three-domain Cry toxins. Single point mutations such as D111K or K115D resulted in proteins severely affected in toxicity...
August 11, 2017: Applied and Environmental Microbiology
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