107 results match your criteria allows head-to-tail

Revisiting the Self-Assembly of Highly Aromatic Phenylalanine Homopeptides.

Molecules 2020 Dec 20;25(24). Epub 2020 Dec 20.

Departament d'Enginyeria Química and Barcelona Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, EEBE, C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain.

Diphenylalanine peptide (FF), which self-assembles into rigid tubular nanostructures, is a very short core recognition motif in Alzheimer's disease β-amyloid (Aβ) polypeptide. Moreover, the ability of the phenylalanine (F or Phe)-homopeptides to self-assemble into ordered nanostructures has been proved. Within this context it was shown that the assembly preferences of this family of compounds is altered by capping both the - and C-termini using highly aromatic fluorenyl groups (i. Read More

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December 2020

Structural basis of carnitine monooxygenase CntA substrate specificity, inhibition and inter-subunit electron transfer.

J Biol Chem 2020 Nov 6. Epub 2020 Nov 6.

University of Warwick, United Kingdom.

Microbial metabolism of carnitine to trimethylamine (TMA) in the gut can accelerate atherosclerosis and heart disease and these TMA-producing enzymes are therefore important drug targets. Here, we report the first structures of the carnitine oxygenase CntA, an enzyme of the Rieske oxygenase family. CntA exists in a head-to-tail a3 trimeric structure. Read More

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November 2020

Mechanistic Analysis of Solid-State Colorimetric Switching: Monoalkoxynaphthalene-Naphthalimide Donor-Acceptor Dyads.

J Am Chem Soc 2020 Oct 29;142(41):17630-17643. Epub 2020 Sep 29.

Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States.

There is growing interest in creating solids that are responsive to various stimuli. Herein we report the first molecular-level mechanistic picture of the thermochromic polymorphic transition in a series of MAN-NI dyad crystals that turn from orange to yellow upon heating with minimal changes to the microscopic morphology following the transition. Detailed structural analyses revealed that the dyads assemble to create an alternating bilayer type structure, with horizontal alternating alkyl and stacked aromatic layers in both the orange and yellow forms. Read More

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October 2020

Concomitant polymorphic forms of 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole.

Acta Crystallogr C Struct Chem 2020 08 30;76(Pt 8):836-844. Epub 2020 Jul 30.

Federal State Autonomous Educational Institution of Higher Education, I.M. Sechenov First Moscow State Medical University, 8 Trubeckaya, Moscow 119991, Russian Federation.

The dipharmacophore compound 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole, CHNO, was studied on the assumption of its potential biological activity. Two concomitant polymorphs were obtained on crystallization from isopropanol solution and these were thoroughly studied. Identical conformations of the molecules are found in both structures despite the low difference in energy between the four possible conformers. Read More

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DIX Domain Polymerization Drives Assembly of Plant Cell Polarity Complexes.

Cell 2020 02 30;180(3):427-439.e12. Epub 2020 Jan 30.

Laboratory of Biochemistry, Wageningen University, Stippeneng 4, Wageningen, the Netherlands. Electronic address:

Cell polarity is fundamental for tissue morphogenesis in multicellular organisms. Plants and animals evolved multicellularity independently, and it is unknown whether their polarity systems are derived from a single-celled ancestor. Planar polarity in animals is conferred by Wnt signaling, an ancient signaling pathway transduced by Dishevelled, which assembles signalosomes by dynamic head-to-tail DIX domain polymerization. Read More

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February 2020


Nat Commun 2019 08 23;10(1):3820. Epub 2019 Aug 23.

Institute of Microbial Chemistry, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo, 141-0021, Japan.

The bottom-up synthesis of structurally well-defined motifs of graphitic materials is crucial to understanding their physicochemical properties and to elicit new functions. Herein, we report the design and synthesis of TriQuinoline (TQ) as a molecular model for pyridinic-nitrogen defects in graphene sheets. TQ is a trimer of quinoline units concatenated at the 2- and 8-positions in a head-to-tail fashion, whose structure leads to unusual aromatisation behaviour at the final stage of the synthesis. Read More

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Exploring molecular tools for transformation and gene expression in the cultivated edible mushroom Agrocybe aegerita.

Mol Genet Genomics 2019 Jun 18;294(3):663-677. Epub 2019 Feb 18.

Junior Research Group Genetics and Genomics of Fungi, Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Senckenberganlage 25, 60325, Frankfurt am Main, Germany.

Agrocybe aegerita is a cultivated edible mushroom in numerous countries, which also serves as a model basidiomycete to study fruiting body formation. Aiming to create an easily expandable customised molecular toolset for transformation and constitutive gene of interest expression, we first created a homologous dominant marker for transformant selection. Progeny monokaryons of the genome-sequenced dikaryon A. Read More

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Interactions of tropomyosin Tpm1.1 on a single actin filament: A method for extraction and processing of high resolution TIRF microscopy data.

PLoS One 2018 10;13(12):e0208586. Epub 2018 Dec 10.

School of Mathematics & Statistics, University of New South Wales, Sydney, New South Wales, Australia.

Skeletal muscle tropomyosin (Tpm1.1) is an elongated, rod-shaped, alpha-helical coiled-coil protein that forms continuous head-to-tail polymers along both sides of the actin filament. In this study we use single molecule fluorescence TIRF microscopy combined with a microfluidic device and fluorescently labelled proteins to measure Tpm1. Read More

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MT1-MMP Binds Membranes by Opposite Tips of Its β Propeller to Position It for Pericellular Proteolysis.

Structure 2019 02 21;27(2):281-292.e6. Epub 2018 Nov 21.

Department of Biochemistry, University of Missouri, 117 Schweitzer Hall, Columbia, MO 65211, USA. Electronic address:

Critical to migration of tumor cells and endothelial cells is the proteolytic attack of membrane type 1 matrix metalloproteinase (MT1-MMP) upon collagen, growth factors, and receptors at cell surfaces. Lipid bilayer interactions of the substrate-binding hemopexin-like (HPX) domain of MT1-MMP were investigated by paramagnetic nuclear magnetic resonance relaxation enhancements (PREs), fluorescence, and mutagenesis. The HPX domain binds bilayers by blades II and IV on opposite sides of its β propeller fold. Read More

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February 2019

Selective Elimination of the Key Subunit Interfaces Facilitates Conversion of Native 24-mer Protein Nanocage into 8-mer Nanorings.

J Am Chem Soc 2018 10 22;140(43):14078-14081. Epub 2018 Oct 22.

Key Laboratory of Chemical Biology and Molecular Engineering of Education Ministry, Institute of Molecular Science , Shanxi University , Taiyuan 030006 , China.

Living systems utilize proteins as building blocks to construct a large variety of self-assembled nanoscale architectures. Yet, creating protein-based assemblies with specific geometries in the laboratory remains challenging. Here, we present a new approach that completely eliminates one natural intersubunit interface of multisubunit protein architecture with high symmetry, resulting in reassembly of the protein architecture into one with lower symmetry. Read More

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October 2018

Supersymmetry-guided method for mode selection and optimization in coupled systems.

Opt Lett 2018 Aug;43(15):3758-3761

Single-mode operation of coupled optical systems, such as optical-fiber bundles, lattices of photonic waveguides, or laser arrays, requires an efficient method to suppress unwanted super-modes. Here, we propose a systematic supersymmetry-based approach to selectively eliminate modes of such systems by decreasing their lifetime relative to the lifetime of the mode of interest. The proposed method allows to explore the opto-geometric parameters of the coupled system and to maximize the relative lifetime of a selected mode. Read More

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Replication Fork Breakage and Restart in Escherichia coli.

Microbiol Mol Biol Rev 2018 09 13;82(3). Epub 2018 Jun 13.

Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom

In all organisms, replication impairments are an important source of genome rearrangements, mainly because of the formation of double-stranded DNA (dsDNA) ends at inactivated replication forks. Three reactions for the formation of dsDNA ends at replication forks were originally described for and became seminal models for all organisms: the encounter of replication forks with preexisting single-stranded DNA (ssDNA) interruptions, replication fork reversal, and head-to-tail collisions of successive replication rounds. Here, we first review the experimental evidence that now allows us to know when, where, and how these three different reactions occur in . Read More

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September 2018

Plant SAM-Domain Proteins Start to Reveal Their Roles.

Trends Plant Sci 2017 08 28;22(8):718-725. Epub 2017 Jun 28.

LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000 Grenoble, France. Electronic address:

Proteins often act in complexes assembled via protein-protein interaction domains. The sterile alpha motif (SAM) domain is one of the most prominent interaction domains in animals and is present in proteins of diverse functions. This domain allows head-to-tail closed oligomerisation or polymer formation resulting in homo- and/or heterocomplexes that have been shown to be important for proper protein localisation and function. Read More

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Adenylyl cyclase mRNA localizes to the posterior of polarized DICTYOSTELIUM cells during chemotaxis.

BMC Cell Biol 2017 05 25;18(1):23. Epub 2017 May 25.

Laboratory of Cellular and Molecular Biology, Center for Cancer Research, 37 Convent Drive, Bldg.37/Rm2066, NCI, NIH, Bethesda, MD, 20892-4256, USA.

Background: In Dictyostelium discoideum, vesicular transport of the adenylyl cyclase A (ACA) to the posterior of polarized cells is essential to relay exogenous 3',5'-cyclic adenosine monophosphate (cAMP) signals during chemotaxis and for the collective migration of cells in head-to-tail arrangements called streams.

Results: Using fluorescence in situ hybridization (FISH), we discovered that the ACA mRNA is asymmetrically distributed at the posterior of polarized cells. Using both standard estimators and Monte Carlo simulation methods, we found that the ACA mRNA enrichment depends on the position of the cell within a stream, with the posterior localization of ACA mRNA being strongest for cells at the end of a stream. Read More

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Solid-phase synthesis, cyclization, and site-specific functionalization of aziridine-containing tetrapeptides.

Nat Protoc 2017 Jun 24;12(6):1277-1287. Epub 2017 May 24.

Department of Chemistry, Davenport Research Laboratories, University of Toronto, Toronto, Ontario, Canada.

Cyclic tetrapeptides comprise a potent and selective class of molecules with a wide range of biological activities, including the phytotoxic activity of tentoxin and the histone deacetylase (HDAC) inhibitory effects of chlamydocin. The incorporation of a functional aziridine group within cyclic peptides enables their conformational control and allows for late-stage and site-selective functionalization of these molecules, thereby creating the potential for covalent protein labeling. This protocol describes the solid-phase synthesis, cyclization, and site-specific structural modification of aziridine-containing tetrapeptides. Read More

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Self-Assembly of Conjugated Metallopolymers with Tunable Length and Controlled Regiochemistry.

Angew Chem Int Ed Engl 2017 06 23;56(26):7541-7545. Epub 2017 May 23.

Chemistry Department, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.

Self-assembled materials can be designed to express useful optoelectronic properties; however, achieving structural control is a necessary precondition for the optimization of desired properties. Here we report a simple, metal-templated polymerization process that generates helical metallopolymer strands over 75 repeat units long (28 kDa) from a single bifunctional monomer and Cu . The resulting polymer consists of a double helix of two identical conjugated organic strands enclosing a central column of metal ions. Read More

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On-site Direct Detection of Astaxanthin from Salmon Fillet Using Raman Spectroscopy.

Mar Biotechnol (NY) 2017 Apr 4;19(2):157-163. Epub 2017 Apr 4.

Integrated Institute for Regulatory Science, Research Organization for Nano and Life Innovation, Waseda University, 513 Tsurumaki-cho, Sbinjuku-ku, Tokyo, 162-0041, Japan.

A new technology employing Raman spectroscopy is attracting attention as a powerful biochemical technique for the detection of beneficial and functional food nutrients, such as carotenoids and unsaturated fatty acids. This technique allows for the dynamic characterization of food nutrient substances for the rapid determination of food quality. In this study, we attempt to detect and measure astaxanthin from salmon fillets using this technology. Read More

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Polarization and migration in the zebrafish posterior lateral line system.

PLoS Comput Biol 2017 04 3;13(4):e1005451. Epub 2017 Apr 3.

Department of Mathematics, University of British Columbia, Vancouver, British Columbia, Canada.

Collective cell migration plays an important role in development. Here, we study the posterior lateral line primordium (PLLP) a group of about 100 cells, destined to form sensory structures, that migrates from head to tail in the zebrafish embryo. We model mutually inhibitory FGF-Wnt signalling network in the PLLP and link tissue subdivision (Wnt receptor and FGF receptor activity domains) to receptor-ligand parameters. Read More

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Molecular Aggregate Photophysics beyond the Kasha Model: Novel Design Principles for Organic Materials.

Acc Chem Res 2017 02 1;50(2):341-350. Epub 2017 Feb 1.

Department of Chemistry Temple University Philadelphia, Pennsylvania 19122, United States.

The transport and photophysical properties of organic molecular aggregates, films, and crystals continue to receive widespread attention, driven mainly by expanding commercial applications involving display and wearable technologies as well as the promise of efficient, large-area solar cells. The main blueprint for understanding how molecular packing impacts photophysical properties was drafted over five decades ago by Michael Kasha. Kasha showed that the Coulombic coupling between two molecules, as determined by the alignment of their transition dipoles, induces energetic shifts in the main absorption spectral peak and changes in the radiative decay rate when compared to uncoupled molecules. Read More

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February 2017

Ion pairing controls rheological properties of "processionary" polyelectrolyte hydrogels.

Soft Matter 2016 Dec;12(48):9749-9758

Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Villeurbanne, France.

We demonstrated recently that polyelectrolytes with cationic moieties along the chain and a single anionic head are able to form physical hydrogels due to the reversible nature of the head-to-body ionic bond. Here we generate a variety of such polyelectrolytes with various cationic moieties and counterion combinations starting from a common polymeric platform. We show that the rheological properties (shear modulus, critical strain) of the final hydrogels can be modulated over three orders of magnitude depending on the cation/anion pair. Read More

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December 2016

Transport and Organization of Cholesterol in a Planar Solid-Supported Lipid Bilayer Depend on the Phospholipid Flip-Flop Rate.

Langmuir 2016 11 31;32(44):11681-11689. Epub 2016 Oct 31.

Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics and ‡Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China , Hefei, Anhui 230026, China.

Understanding the transport behavior of the cholesterol molecules within a cell membrane is a key challenge in cell biology at present. Here, we have applied sum frequency generation vibrational spectroscopy to characterize the transport and organization of cholesterol in different kinds of planar solid-supported lipid bilayers by combining achiral- and chiral-sensitive polarization measurements. This method allows us to distinguish the organization of cholesterol in tail-to-tail, head-to-tail, head-to-head, and side-by-side manners. Read More

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November 2016

Variation of 45S rDNA intergenic spacers in Arabidopsis thaliana.

Plant Mol Biol 2016 Nov 16;92(4-5):457-471. Epub 2016 Aug 16.

Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic.

Approximately seven hundred 45S rRNA genes (rDNA) in the Arabidopsis thaliana genome are organised in two 4 Mbp-long arrays of tandem repeats arranged in head-to-tail fashion separated by an intergenic spacer (IGS). These arrays make up 5 % of the A. thaliana genome. Read More

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November 2016

Tankyrase Requires SAM Domain-Dependent Polymerization to Support Wnt-β-Catenin Signaling.

Mol Cell 2016 08;63(3):498-513

Division of Structural Biology, The Institute of Cancer Research (ICR), London SW7 3RP, UK; Division of Cancer Biology, The Institute of Cancer Research (ICR), London SW7 3RP, UK. Electronic address:

The poly(ADP-ribose) polymerase (PARP) Tankyrase (TNKS and TNKS2) is paramount to Wnt-β-catenin signaling and a promising therapeutic target in Wnt-dependent cancers. The pool of active β-catenin is normally limited by destruction complexes, whose assembly depends on the polymeric master scaffolding protein AXIN. Tankyrase, which poly(ADP-ribosyl)ates and thereby destabilizes AXIN, also can polymerize, but the relevance of these polymers has remained unclear. Read More

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Asymmetric Organocatalytic Stepwise [2+2] Entry to Tetra-Substituted Heterodimeric and Homochiral Cyclobutanes.

Chemistry 2016 Jun 24;22(27):9111-5. Epub 2016 May 24.

Department of Chemistry and Chemical-Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1, Canada.

An asymmetric synthesis of tetra-substituted cyclobutanes involving an organocatalytic, stepwise [2+2]-cycloaddition is described. The secondary-amine-catalyzed method allows for the hetero-dimerization of two different cinnamic-acid-derived sub-units, opening a novel one-step assembly to densely functionalized, head-to-tail coupled dimeric cyclobutanes in high enantiomeric excess. A series of selective synthetic interconversions in these sensitive cycloadducts is also described. Read More

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A Novel Carcinoembryonic Antigen T-Cell Bispecific Antibody (CEA TCB) for the Treatment of Solid Tumors.

Clin Cancer Res 2016 07 9;22(13):3286-97. Epub 2016 Feb 9.

Oncology Discovery, Roche Innovation Center Zurich, Roche Pharmaceutical Research and Early Development, pRED, Zurich, Switzerland.

Purpose: CEA TCB is a novel IgG-based T-cell bispecific (TCB) antibody for the treatment of CEA-expressing solid tumors currently in phase I clinical trials (NCT02324257). Its format incorporates bivalent binding to CEA, a head-to-tail fusion of CEA- and CD3e-binding Fab domains and an engineered Fc region with completely abolished binding to FcγRs and C1q. The study provides novel mechanistic insights into the activity and mode of action of CEA TCB. Read More

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Use of the Nanofitin Alternative Scaffold as a GFP-Ready Fusion Tag.

PLoS One 2015 5;10(11):e0142304. Epub 2015 Nov 5.

Affilogic SAS, Nantes, France.

With the continuous diversification of recombinant DNA technologies, the possibilities for new tailor-made protein engineering have extended on an on-going basis. Among these strategies, the use of the green fluorescent protein (GFP) as a fusion domain has been widely adopted for cellular imaging and protein localization. Following the lead of the direct head-to-tail fusion of GFP, we proposed to provide additional features to recombinant proteins by genetic fusion of artificially derived binders. Read More

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Tropomyosin - master regulator of actin filament function in the cytoskeleton.

J Cell Sci 2015 Aug 3;128(16):2965-74. Epub 2015 Aug 3.

School of Biosciences, Stacey Building, University of Kent, Canterbury, Kent CT2 7NJ, UK.

Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Read More

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A corpora allata farnesyl diphosphate synthase in mosquitoes displaying a metal ion dependent substrate specificity.

Insect Biochem Mol Biol 2015 Sep 15;64:44-50. Epub 2015 Jul 15.

Department of Biological Sciences, Florida International University, Miami, FL 33199, USA. Electronic address:

Farnesyl diphosphate synthase (FPPS) is a key enzyme in isoprenoid biosynthesis, it catalyzes the head-to-tail condensation of dimethylallyl diphosphate (DMAPP) with two molecules of isopentenyl diphosphate (IPP) to generate farnesyl diphosphate (FPP), a precursor of juvenile hormone (JH). In this study, we functionally characterized an Aedes aegypti FPPS (AaFPPS) expressed in the corpora allata. AaFPPS is the only FPPS gene present in the genome of the yellow fever mosquito, it encodes a 49. Read More

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September 2015

Direct synthesis of macrodiolides via hafnium(IV) catalysis.

Chem Commun (Camb) 2015 Jul;51(52):10471-4

Department of Chemistry and Centre for Green Chemistry and Catalysis, Université de Montréal, CP 6128 Station Downtown, Montréal, Québec H3C 3J7, Canada.

Efficient direct synthesis of macrodiolides via catalysis using Hf(OTf)4 is possible in high yields, forming water as the sole by-product. The first protocol for the direct synthesis of macrodiolides from equimolar mixtures of diols and dicarboxylic acids was developed (58-96%). In addition, modification of the reaction concentration allows for the synthesis of head-to-tail macrodiolides from the corresponding seco acids. Read More

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Direct observations of field-induced assemblies in magnetite ferrofluids.

J Appl Phys 2015 Mar 11;117(10):103907. Epub 2015 Mar 11.

New York University Abu Dhabi , Saadiyat Island, PO Box 129 188, Abu Dhabi, United Arab Emirates.

Evolution of microstructures in magnetite-based ferrofluids with weak dipolar moments (particle size ≤ 10 nm) is studied with an emphasis on examining the effects of particle concentration () and magnetic field strength () on the structures. Nanoparticles are dispersed in water at three different concentrations,  = 0.15%, 0. Read More

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