I03-Macromolecular Crystallography
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Patrick F.
Conlon
,
Olga
Eguaogie
,
Jordan J.
Wilson
,
Jamie S. T.
Sweet
,
Julian
Steinhoegl
,
Klaudia
Englert
,
Oliver G. A.
Hancox
,
Christopher J.
Law
,
Sarah A.
Allman
,
James H. R.
Tucker
,
James P.
Hall
,
Joseph S.
Vyle
Diamond Proposal Number(s):
[20077, 20214]
Open Access
Abstract: Oligodeoxynucleotides incorporating internucleotide phosphoroselenolate linkages have been prepared under solid-phase synthesis conditions using dimer phosphoramidites. These dimers were constructed following the high yielding Michaelis–Arbuzov (M–A) reaction of nucleoside H-phosphonate derivatives with 5′-deoxythymidine-5′-selenocyanate and subsequent phosphitylation. Efficient coupling of the dimer phosphoramidites to solid-supported substrates was observed under both manual and automated conditions and required only minor modifications to the standard DNA synthesis cycle. In a further demonstration of the utility of M–A chemistry, the support-bound selenonucleoside was reacted with an H-phosphonate and then chain extended using phosphoramidite chemistry. Following initial unmasking of methyl-protected phosphoroselenolate diesters, pure oligodeoxynucleotides were isolated using standard deprotection and purification procedures and subsequently characterised by mass spectrometry and circular dichroism. The CD spectra of both modified and native duplexes derived from self-complementary sequences with A-form, B-form or mixed conformational preferences were essentially superimposable. These sequences were also used to study the effect of the modification upon duplex stability which showed context-dependent destabilisation (−0.4 to −3.1 °C per phosphoroselenolate) when introduced at the 5′-termini of A-form or mixed duplexes or at juxtaposed central loci within a B-form duplex (−1.0 °C per modification). As found with other nucleic acids incorporating selenium, expeditious crystallisation of a modified decanucleotide A-form duplex was observed and the structure solved to a resolution of 1.45 Å. The DNA structure adjacent to the modification was not significantly perturbed. The phosphoroselenolate linkage was found to impart resistance to nuclease activity.
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Oct 2019
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[15777, 17193]
Open Access
Abstract: Organic molecules tend to close pack to form dense structures when they are crystallised from organic solvents. Porous molecular crystals defy this rule: they contain open space, which is typically stabilised by inclusion of solvent in the interconnected pores during crystallisation. The design and discovery of such structures is often challenging and time consuming, in part because it is difficult to predict solvent effects on crystal form stability. Here, we combine crystal structure prediction (CSP) with a robotic crystallisation screen to accelerate the discovery of stable hydrogen-bonded frameworks. We exemplify this strategy by finding new phases of two well-studied molecules in a computationally targeted way. Specifically, we find a new ‘hidden’ porous polymorph of trimesic acid, δ-TMA, that has a guest-free hexagonal pore structure, as well as three new solvent-stabilized diamondoid frameworks of adamantane-1,3,5,7-tetracarboxylic acid (ADTA). Beyond porous solids, this hybrid computational–experimental approach could be applied to a wide range of materials problems, such as organic electronics and drug formulation.
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Sep 2019
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I02-Macromolecular Crystallography
I04-Macromolecular Crystallography
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Marta
Artola
,
Christinne
Hedberg
,
Rhianna J.
Rowland
,
Lluís
Raich
,
Kassiani
Kytidou
,
Liang
Wu
,
Amanda
Schaaf
,
Maria Joao
Ferraz
,
Gijsbert A.
Van Der Marel
,
Jeroen D. C.
Codée
,
Carme
Rovira
,
Johannes M. F. G.
Aerts
,
Gideon J.
Davies
,
Herman S.
Overkleeft
Diamond Proposal Number(s):
[13587]
Open Access
Abstract: Fabry disease is an inherited lysosomal storage disorder that is characterized by a deficiency in lysosomal α-D-galactosidase activity. One current therapeutic strategy involves enzyme replacement therapy, in which patients are treated with a recombinant enzyme. Co-treatment with enzyme active-site stabilizers is advocated to increase treatment efficacy, a strategy that requires effective and selective enzyme stabilizers. Here, we describe the design and development of an α-D-gal-cyclophellitol cyclosulfamidate as a new class of neutral, conformationally constrained competitive glycosidase inhibitors that act by mimicry of the Michaelis complex conformation. We found that D-galactose-configured α-cyclosulfamidate 4 effectively stabilizes recombinant human α-D-galactosidase (agalsidase beta, Fabrazyme®) both in vitro and in cellulo.
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Aug 2019
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B21-High Throughput SAXS
B23-Circular Dichroism
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Wenjin
Xiao
,
Thomas I. P.
Green
,
Xiaowen
Liang
,
Rosalia Cuahtecontzi
Delint
,
Guillaume
Perry
,
Michael S.
Roberts
,
Kristian
Le Vay
,
Catherine R.
Back
,
Raimomdo
Ascione
,
Haolu
Wang
,
Paul R.
Race
,
Adam W.
Perriman
Open Access
Abstract: We present a new cell membrane modification methodology where the inherent heart tissue homing properties of the infectious bacteria Streptococcus gordonii are transferred to human stem cells. This is achieved via the rational design of a chimeric protein–polymer surfactant cell membrane binding construct, comprising the cardiac fibronectin (Fn) binding domain of the bacterial adhesin protein CshA fused to a supercharged protein. Significantly, the protein–polymer surfactant hybrid spontaneously inserts into the plasma membrane of stem cells without cytotoxicity, instilling the cells with a high affinity for immobilized fibronectin. Moreover, we show that this cell membrane reengineering approach significantly improves retention and homing of stem cells delivered either intracardially or intravenously to the myocardium in a mouse model.
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Jul 2019
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I22-Small angle scattering & Diffraction
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Open Access
Abstract: A polymerizable amphiphile having two zwitterionic head-groups has been designed. This compound co-organizes with an acid, bis(trifluoromethanesulfonyl)imide (HTf2N), into a gyroid bicontinuous cubic liquid-crystalline phase. In situ polymerization of this phase has been successfully achieved by UV irradiation in the presence of a photoinitiator, yielding a self-standing gyroid-nanostructured polymer film. When the polymer film is placed under different relative humidity conditions or in water, it absorbs water owing to the strong hydration ability of the zwitterionic parts. It has been found that the polymer film preserves the gyroid nanostructure after the water absorption. Based on reconstructed electron density maps, it is assumed that the absorbed water molecules form a 3D continuous network along the gyroid minimal surface, which satisfies several key conditions for inducing fast proton conduction. As expected, such hydrated films show high ionic conductivities in the order of 10−1 S cm−1 when the water content of the film reaches 15.6 wt% at RH = 90%. The high conductivity is attributed to the induction of the Grotthuss mechanism, that is, proton conduction via the hydrogen-bonding network of the incorporated water molecules.
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Jun 2019
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I22-Small angle scattering & Diffraction
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Open Access
Abstract: It is well-known that the Dengue fever virus undergoes a distinct morphological transition from topologically smooth particles to ‘bumpy’ particle on increasing the temperature from that of the mosquito carrier (28 °C) to that of the human host (37 °C). This virus also possesses pH-sensitive surface domains that undergo conformational changes during infection which facilitates exit from the endosomes. Herein we take a bio-inspired approach to design synthetic Dengue virus-mimicking nanoparticles to target triple-negative (TN) breast cancer cells that overexpress SR-B1 scavenger receptors. Thus, sterile pH-responsive methacrylic ABC triblock copolymer vesicles were prepared in aqueous solution via polymerization-induced self-assembly. Microphase separation between two enthalpically-incompatible hydrophobic membrane-forming blocks produced a well-defined framboidal morphology, with surface globules of ∼28 nm diameter protruding from the membrane. The hydrophilic stabilizer block comprises 97% hydroxyl-functionalized chains and 3% phosphorylcholine-functionalized chains, with the latter being critical for selective intracellular uptake. These framboidal vesicles remain intact at neutral pH but become swollen and cationic at pH 5–6 because the tertiary amine residues in the hydrophobic C block become protonated. We demonstrate that such nanoparticles enable selective targeting of TN breast cancer cells. This is because such malignant cells overexpress SR-B1 receptors for naturally-occurring phospholipids and hence take up the phosphorylcholine-decorated framboidal vesicles preferentially. In contrast, negligible cell uptake is observed over the same time period for both human dermal fibroblasts and normal breast cancer cells that minimally express the SR-B1 receptor. Moreover, we show that genetic material within such pH-responsive framboidal vesicles can be efficiently delivered to the cell nuclei while maintaining high cell viability.
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May 2019
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I15-Extreme Conditions
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D.
Santamaria-perez
,
D.
Daisenberger
,
J.
Ruiz-fuertes
,
T.
Marqueno
,
R.
Chulia-jordan
,
C.
Muehle
,
M.
Jansen
,
P.
Rodriguez-hernandez
,
A.
Muñoz
,
Erin R.
Johnson
,
A.
Otero-de-la-roza
Diamond Proposal Number(s):
[16212]
Open Access
Abstract: We report the experimental high-pressure crystal structure and equation of state of gold(I) sulfide (Au2S) determined using diamond-anvil cell synchrotron X-ray diffraction. Our data shows that Au2S has a simple cubic structure with six atoms in the unit cell (four Au in linear, and two S in tetrahedral, coordination), no internal degrees of freedom, and relatively low bulk modulus. Despite its structural simplicity, Au2S displays very unusual chemical bonding. The very similar and relatively high electronegativities of Au and S rule out any significant metallic or ionic character. Using a simple valence bond (Lewis) model, we argue that the Au2S crystal possesses two different types of covalent bonds: dative and shared. These bonds are distributed in such a way that each Au atom engages in one bond of each kind. The multiple arrangements in space of dative and shared bonds are degenerate, and the multiplicity of configurations imparts the system with multireference character, which is highly unusual for an extended solid. The other striking feature of this system is that common computational (DFT) methods fail quite spectacularly to describe it, with 20% and 400% errors in the equilibrium volume and bulk modulus, respectively. We explain this by the poor treatment of static correlation in common density-functional approximations. The fact that the solid is structurally very simple, yet presents unique chemical bonding and is unmodelable using current DFT methods, makes it an interesting case study and a computational challenge.
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May 2019
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[13639]
Open Access
Abstract: Double metal cyanides (DMCs) are well known, industrially applied catalysts for ring opening polymerization reactions. In recent years, they have been studied for a variety of catalytic reactions, as well as other applications, such as energy storage and Cs sorption. Herein, a new, layered DMC phase (L-DMC), Zn2[Co(CN)6](CH3COO)·4H2O, was synthesized. The structure, which crystallizes in the monoclinic space group P21/m, consists of positively charged {Zn2Co(CN)6}+ DMC layers linked through acetate groups and presents a new layered structure to the family of double metal cyanides. L-DMC proved to be a reusable and stable catalyst that exhibited a higher activity than the benchmark DMC catalyst in two important applications: hydroamination of phenylacetylene with 4-isopropylaniline and polymerization of 1,2-epoxyhexane.
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Apr 2019
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I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[18548]
Open Access
Abstract: The discovery of new Protein–Protein Interaction (PPI) modulators is currently limited by the difficulties associated with the design and synthesis of selective small molecule inhibitors. Peptides are a potential solution for disrupting PPIs; however, they typically suffer from poor stability in vivo and limited tissue penetration hampering their wide spread use as new chemical biology tools and potential therapeutics. In this work, a combination of CuAAC chemistry, molecular modelling, X-ray crystallography, and biological validation allowed us to develop highly functionalised peptide PPI inhibitors of the protein CK2. The lead peptide, CAM7117, prevents the formation of the holoenzyme assembly in vitro, slows down proliferation, induces apoptosis in cancer cells and is stable in human serum. CAM7117 could aid the development of novel CK2 inhibitors acting at the interface and help to fully understand the intracellular pathways involving CK2. Importantly, the approach adopted herein could be applied to many PPI targets and has the potential to ease the study of PPIs by efficiently providing access to functionalised peptides.
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Apr 2019
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I07-Surface & interface diffraction
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Victor
Rubio-gimenez
,
Carlos
Bartual-murgui
,
Marta
Galbiati
,
Alejandro
Núñez-lópez
,
Javier
Castells-gil
,
Benoit
Quinard
,
Pierre
Seneor
,
Edwige
Otero
,
Philippe
Ohresser
,
Andrés
Cantarero
,
Eugenio
Coronado
,
José Antonio
Real
,
Richard
Mattana
,
Sergio
Tatay
,
Carlos
Martí-gastaldo
Diamond Proposal Number(s):
[14495]
Open Access
Abstract: Mastering the nanostructuration of molecular materials onto solid surfaces and understanding how this process affects their properties are of utmost importance for their integration into solid-state electronic devices. This is even more important for spin crossover (SCO) systems, in which the spin transition is extremely sensitive to size reduction effects. These bi-stable materials have great potential for the development of nanotechnological applications provided their intrinsic properties can be successfully implemented in nanometric films, amenable to the fabrication of functional nanodevices. Here we report the fabrication of crystalline ultrathin films (<1–43 nm) of two-dimensional Hofmann-type coordination polymers by using an improved layer-by-layer strategy and a close examination of their SCO properties at the nanoscale. X-ray absorption spectroscopy data in combination with extensive atomic force microscopy analysis reveal critical dependence of the SCO transition on the number of layers and the microstructure of the films. This originates from the formation of segregated nanocrystals in early stages of the growth process that coalesce into a continuous film with an increasing number of growth cycles for an overall behaviour reminiscent of the bulk. As a result, the completeness of the high spin/low spin transition is dramatically hindered for films of less than 15 layers revealing serious limitations to the ultimate thickness that might be representative of the performance of the bulk when processing SCO materials as ultrathin films. This unprecedented exploration of the particularities of the growth of SCO thin films at the nanoscale should encourage researchers to put a spotlight on these issues when contemplating their integration into devices.
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Feb 2019
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