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https://www.readbyqxmd.com/read/28636257/covalent-attachment-and-pro-pro-endopeptidase-ppep-1-mediated-release-of-clostridium-difficile-cell-surface-proteins-involved-in-adhesion
#1
REVIEW
Jeroen Corver, Valentina Cordo', Hans C van Leeuwen, Oleg I Klychnikov, Paul J Hensbergen
In the past decade, Clostridium difficile has emerged as an important gut pathogen. This anaerobic, Gram-positive bacterium is the main cause of infectious nosocomial diarrhea. Whereas much is known about the mechanism through which the C. difficile toxins cause diarrhea, relatively little is known about the dynamics of adhesion and motility, which is mediated by cell surface proteins. This review will discuss the recent advances in our understanding of the sortase-mediated covalent attachment of cell surface (adhesion) proteins to the peptidoglycan layer of C...
June 21, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28636148/magneto-structural-characterization-of-oxalamide-dihalo-bridged-copper-dimers-intra-and-interdimer-interactions-studied-by-single-crystal-esr-spectroscopy
#2
Dijana Zilic, Debdeep Maity, Mario Cetina, Kresimir Molcanov, Zoran Dzolic, Mirta Herak
The detailed single crystal electron spin resonance (ESR) analysis of oxalamide complexes with halogen-bridged copper dimers, supported by X-ray, magnetic susceptibility and powder ESR studies, is reported. Four complexes with two different ligands were synthesized: [CuLA(μ-X)]₂ and [CuLV(μ-X)]₂, where LA = N-(L-alanine methyl ester)-N'-((2-pyridine-2-yl)methyl)oxalamide and LV=N-(L-valine methyl ester)-N'-((2-pyridine-2-yl)methyl)oxalamide, while X=Cl or Br. X-ray analysis shows that geometry at each copper(II) ion is square pyramidal while two pyramids share one base-to-apex edge with parallel basal planes...
June 21, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28635616/fermi-to-bose-crossover-in-a-trapped-quasi-2d-gas-of-fermionic-atoms
#3
Andrey Turlapov, Maxim Yu Kagan
Physics of many-body systems where particles are restricted to move in two spatial dimensions is challenging and even controversial: On one hand, neither long-range order nor Bose condensation may appear in infinite uniform 2D systems at finite temperature, on the other hand this does not prohibit superfluidity or superconductivity. Moreover, 2D superconductors, such as cuprates, are among the systems with highest critical temperatures. Ultracold atoms are a platform for studying 2D physics. Uniquely to other physical systems, quantum statistics may be completely changed in an ultracold gas: an atomic Fermi gas may be smoothly crossed over into a gas of Bose molecules (or dimers) by tuning interatomic interactions...
June 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28634302/structure-of-human-fe-s-assembly-subcomplex-reveals-unexpected-cysteine-desulfurase-architecture-and-acyl-acp-isd11-interactions
#4
Seth A Cory, Jonathan G Van Vranken, Edward J Brignole, Shachin Patra, Dennis R Winge, Catherine L Drennan, Jared Rutter, David P Barondeau
In eukaryotes, sulfur is mobilized for incorporation into multiple biosynthetic pathways by a cysteine desulfurase complex that consists of a catalytic subunit (NFS1), LYR protein (ISD11), and acyl carrier protein (ACP). This NFS1-ISD11-ACP (SDA) complex forms the core of the iron-sulfur (Fe-S) assembly complex and associates with assembly proteins ISCU2, frataxin (FXN), and ferredoxin to synthesize Fe-S clusters. Here we present crystallographic and electron microscopic structures of the SDA complex coupled to enzyme kinetic and cell-based studies to provide structure-function properties of a mitochondrial cysteine desulfurase...
June 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28634233/structural-analyses-of-human-thymidylate-synthase-reveal-a-site-that-may-control-conformational-switching-between-active-and-inactive-states
#5
Dan Chen, Anna Jansson, Daniel Sim, Andreas Larsson, Pär Nordlund
Thymidylate synthase (TS) is the sole enzyme responsible for de novo biosynthesis of thymidylate (TMP) and is essential for cell proliferation and survival. Inhibition of human TS (hTS) has been extensively investigated for cancer chemotherapy, but several aspects of its activity and regulation are still uncertain. In this study, we performed comprehensive structural and biophysical studies of hTS using crystallography and thermal shift assay and provided the first detailed structural information on the conformational changes induced by ligand binding to the hTS active site...
June 20, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28633569/thermal-and-chemical-denaturation-of-colocasia-esculenta-tuber-agglutinin-from-%C3%AE-2%C3%AE-2-to-unfolded-state
#6
Himadri Biswas, Rajagopal Chattopadhyaya
The major tuber storage protein of Colocasia esculenta, is a monocot mannose-binding, widely used dietary lectin, containing two polypeptides of 12.0 and 12.4 kDa. By both gel filtration and dynamic light scattering at pH 7.2, the lectin has a α2β2 form of apparent molecular mass of 48.2 kDa and a hydrodynamic radius of 6.1±0.2 nm; however, at pH 3, it migrates as αβ and has a reduced hydrodynamic radius of 4.6±0.3 nm. Our circular dichroism spectroscopy studies show that the lectin retains approximately 100% of its secondary structure between pH 2-8, going down to ~90% for extreme acidic / alkaline conditions...
June 20, 2017: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/28633073/aggregation-of-n-n-diallylurea-and-n-n-diallylthiourea-in-solutions
#7
REVIEW
Maria Rospenk, Monika Obrzud, Aleksander Koll
Joint studies by IR spectroscopy, dipole moments, average molecular weight measurements and DFT calculations on the self-aggregation of N,N'-diallylureas and N,N'-diallylthioureas in solvents of different polarities were performed. Simultaneous uses of all these methods are required for better understanding the mechanism of aggregation and the effects of different polarity of solvents. In this study also the measurements of IR spectra in polarized light were additionally performed, which gives information on arrangement of aggregates in liquid crystal matrix-built of 4-CN biphenyl derivative...
May 31, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28632987/the-usher-syndrome-type-iiib-histidyl-trna-synthetase-mutation-confers-temperature-sensitivity
#8
Jamie A Abbott, Ethan Guth, Cindy Kim, Cathy Regan, Victoria M Siu, Charles Anthony Rupar, Borries Demeler, Christopher S Francklyn, Susan M Robey-Bond
Histidyl-tRNA synthetase (HARS) is a highly conserved translation factor that plays an essential role in protein synthesis. HARS has been implicated in the human syndromes Charcot-Marie-Tooth (CMT) Type 2W and Type IIIB Usher (USH3B). The USH3B mutation, which encodes an Y454S substitution in HARS, is inherited in an autosomal recessive fashion and associated with childhood deafness, blindness and episodic hallucinations during acute illness. The biochemical basis of the pathophysiologies linked to USH3B is currently unknown...
June 20, 2017: Biochemistry
https://www.readbyqxmd.com/read/28632973/molecular-modeling-study-on-the-tubulin-binding-modes-of-epothilone-derivatives-insight-into-the-structural-basis-for-epothilones-activity
#9
Verónica A Jiménez, Joel B Alderete, Karen R Navarrete
Molecular dynamics (MD) simulations were employed to study the tubulin-binding modes of 20 epothilone derivatives spanning a wide range of antitumor activity. Trajectory analysis revealed that active ligands shared a common region of association and similar binding poses compared to the high-resolution crystal structure of the tubulin complex with epothilone A, the stathmin-like protein RB3, and tubulin tyrosine ligase (PDB code 4I50). Conformational analysis of epothilones in aqueous solution and tubulin-bound states indicated that the bound conformations of active species can be found to a significant extent within the ensemble of conformers available in aqueous solution...
June 20, 2017: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/28632938/mek-inhibitors-induce-akt-activation-and-drug-resistance-by-suppressing-negative-feedback-erk-mediated-her2-phosphorylation-at-thr701
#10
Chia-Hung Chen, Te-Chun Hsia, Ming-Hsin Yeh, Tsung-Wei Chen, Yun-Ju Chen, Jung-Tsu Chen, Ya-Ling Wei, Chih-Yen Tu, Wei-Chien Huang
Targeting the MEK/ERK pathway has been viewed as a promising strategy for cancer therapy. However, MEK inhibition leads to the compensatory PI3K/AKT activation and thus contributes to the desensitization of cancer cells to MEK inhibitors. The underlying molecular mechanism of this event is not yet understood. In this study, our data showed that the induction of Akt activity by MEK inhibitors was specifically observed in HER2-positive breast cancer cells. Silence of HER2, or overexpression of HER2 kinase-dead mutant, prevents the induction of Akt activation in response to MEK inhibition, indicating HER2 as a critical regulator for this event...
June 20, 2017: Molecular Oncology
https://www.readbyqxmd.com/read/28632141/phase-transitions-of-the-dimerized-kane-mele-model-with-without-the-strong-interaction
#11
Tao Du, Yue-Xun Li, Yan Li, He-Lin Lu, Hui Zhang
The dimerized Kane-Mele model with/without the strong interaction is studied using analytical methods. The boundary of the topological phase transition of the model without strong interaction is obtained. Our results show that the occurrence of the transition only depends on dimerized parameter α . From the one-particle spectrum, we obtain the completed phase diagram including the quantum spin Hall (QSH) state and the topologically trivial insulator. Then, using different mean-field methods, we investigate the Mott transition and the magnetic transition of the strongly correlated dimerized Kane-Mele model...
June 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28631856/tetrameric-and-dimeric-n%C3%A2-%C3%A2-%C3%A2-i-%C3%A2-%C3%A2-%C3%A2-n-halogen-bonded-supramolecular-cages
#12
Kari Rissanen, Lotta Turunen, Anssi Peuronen, Samu Forsblom, Elina Kalenius, Manu Lahtinen
Tripodal N-donor ligands are used to form halogen-bonded assemblies via structurally analogous Ag+-complexes. Selective formation of discrete tetrameric I6L4 and dimeric I3L2 halonium cages, wherein multiple [N∙∙∙I+∙∙∙N] halogen bonds are used in concert, can be achieved by using sterically rigidified cationic tris(1-methyl-1-azonia-4-azabicyclo[2.2.2]octane)-mesitylene ligand, L1(PF6)3, and flexible ligand 1,3,5-tris(imidazole-1-ylmethyl)-2,4,6-trimethylbenzene, L2, respectively. The iodonium cages, I6L14(PF6)18 and I3L22(PF6)3, were obtained through the [N∙∙∙Ag+∙∙∙N] → [N∙∙∙I+∙∙∙N] cation exchange reaction between the corresponding Ag6L14(PF6)18 and Ag3L22(PF6)3 coordination cages, prepared as intermediates, and I2...
June 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28631479/quantitative-analysis-of-ligand-induced-hetero-dimerization-of-two-distinct-receptors
#13
Chang Lu, Zhi-Xin Wang
The induced-dimerization of two distinct receptors through a hetero-bifunctional inducer is prevalent among all levels of cellular signaling processes, yet its complexity poses difficulty for systematic quantitative analysis. This paper firstly shows how to calculate the amount of any possible complex or monomer of hetero-ligand and two receptors present at equilibrium. The theory is subsequently applied to the determination of three independent equilibrium parameters involved in the rapamycin induced FKBP and FRB dimerization, in which all parameters were simultaneously estimated using one set of FRET experiments...
June 20, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28631469/the-chemical-composition-of-blackberry-press-cake-polyphenolic-extract-and-defatted-seeds-and-their-effects-on-cecal-fermentation-bacterial-metabolites-and-blood-lipid-profile-in-rats
#14
Monika Kosmala, Adam Jurgonski, Jerzy Juskiewicz, Elżbieta Karlińska, Jakub Macierzyński, Edward Roj, Zenon Zduńczyk
Blackberry fiber (BF), extracted blackberry fiber (EBF), defatted blackberry seeds (DBS) and blackberry polyphenols (BP) were added to diets of rats. A control diet, fiber diets (BF, EBF, DBS) with 6% addition instead of cellulose, a polyphenol diet (BP) with 1% addition were administered for 4 weeks. BF and DBS contained polyphenols (3.6%), EBF did not. DBS was free of fat. Ellagitannins were the main phenolics; mostly dimers (sanguiin H-6 with isomers) and monomers (pedunculagin, casuarictin isomer, and sanguiin H-2 isomer)...
June 20, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28631384/nmr-study-of-the-reductive-decomposition-of-bmim-ntf2-at-gold-electrodes-and-indirect-electrochemical-conversion-of-co2
#15
Roman Michez, Thomas Doneux, Claudine Buess-Herman, Michel Luhmer
Potential controlled electrolyses of [BMIm][NTf2 ] ionic liquid were performed at a gold cathode under nitrogen atmosphere. The structures of the major conversion products of the BMIm(+) cation were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) analyses and gas chromatography (GC) analysis of the volatile compounds. Recombination of the imidazol-2-yl radicals, generated at the electrode by single electron transfer, leads to neutral diastereomeric dimers in equal proportions, with a faradaic efficiency of 80 %, while disproportionation of these radicals and/or reaction with hydrogen atoms adsorbed at the electrode generates a neutral monomer with 20 % faradaic efficiency...
June 20, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28630983/simplified-and-original-wells-rules-plus-age-adjusted-d-dimer-test-were-useful-for-ruling-out-suspected-pe
#16
Alex Gallus
No abstract text is available yet for this article.
June 20, 2017: Annals of Internal Medicine
https://www.readbyqxmd.com/read/28630216/fractionated-dosing-improves-preclinical-therapeutic-index-of-pyrrolobenzodiazepine-containing-antibody-drug-conjugates
#17
Mary Jane Hinrichs, Pauline M Ryan, Bo Zheng, Shameen Afif-Rider, Xiang-Qing Yu, Michele Gunsior, Haihong Zhong, Jay Harper, Binyam Bezabeh, Kapil Vashisht, Marlon Rebelatto, Molly Reed, Patricia C Ryan, Shannon Breen, Neki Patel, Cui Chen, Luke A Masterson, Arnaud Tiberghien, Philip W Howard, Nazzareno Dimasi, Rakesh Dixit
                Purpose:  To use preclinical models to identify a dosing schedule that improves tolerability of highly potent pyrrolobenzodiazepine dimers (PBD) antibody drug conjugates (ADCs) without compromising anti-tumor activity.  <p>                Experimental design:   A series of dose-fractionation studies were conducted to investigate the pharmacokinetic drivers of safety and efficacy of PBD ADCs in animal models.  The exposure-activity relationship was investigated in mouse xenograft models of human prostate cancer, breast and gastric cancer by comparing anti-tumor activity after single and fractionated dosing with tumor-targeting ADCs conjugated to SG3249, a potent PBD dimer...
June 19, 2017: Clinical Cancer Research: An Official Journal of the American Association for Cancer Research
https://www.readbyqxmd.com/read/28630157/pore-formation-by-dimeric-bak-and-bax-an-unusual-pore
#18
REVIEW
Rachel T Uren, Sweta Iyer, Ruth M Kluck
Apoptotic cell death via the mitochondrial pathway occurs in all vertebrate cells and requires the formation of pores in the mitochondrial outer membrane. Two Bcl-2 protein family members, Bak and Bax, form these pores during apoptosis, and how they do so has been investigated for the last two decades. Many of the conformation changes that occur during their transition to pore-forming proteins have now been delineated. Notably, biochemical, biophysical and structural studies indicate that symmetric homodimers are the basic unit of pore formation...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28630140/three-dimensional-structure-of-the-3-x-tail-of-hepatitis-c-virus-rna-in-monomeric-and-dimeric-states
#19
Angel Cantero-Camacho, Lixin Fan, Yun-Xing Wang, José Gallego
The 3'X domain is a 98-nucleotide region located at the 3' end of hepatitis C virus genomic RNA that plays essential functions in the viral life cycle. It contains an absolutely conserved, 16-base palindromic sequence that promotes viral RNA dimerization, overlapped with a 7-nucleotide tract implicated in a distal contact with a nearby functional sequence. Using small angle X-ray scattering measurements combined with model building guided by NMR spectroscopy, we have studied the stoichiometry, structure and flexibility of domain 3'X and two smaller subdomain sequences as a function of ionic strength, and obtained a three-dimensional view of the full-length domain in its monomeric and dimeric states...
June 19, 2017: RNA
https://www.readbyqxmd.com/read/28630139/functional-interfaces-between-ticam-2-tram-and-ticam-1-trif-in-tlr4-signaling
#20
REVIEW
Kenji Funami, Misako Matsumoto, Hiroyuki Oshiumi, Fuyuhiko Inagaki, Tsukasa Seya
Toll-like receptor 4 (TLR4) recognizes lipopolysaccharide (LPS), produces pro-inflammatory cytokines and type I interferons, and associates with a trigger of endotoxin shock. TLR4 is interacted with a TIR domain-containing adaptor molecule-2 (TICAM-2)/TRAM [TRIF (TIR domain-containing adaptor-inducing interferon-β)-related adaptor molecule] via its Toll-interleukin-1 receptor homology (TIR) domain. TICAM-2 acts as a scaffold protein and activates TIR domain-containing adaptor molecule-1 (TICAM-1)/TRIF. According to the structural analysis by NMR, TICAM-2 interacts with TICAM-1 by the acidic amino acids motif, E87/D88/D89...
June 19, 2017: Biochemical Society Transactions
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