Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

10,767 items found (0 items not approved), displaying 61 to 70.[First/Prev] 3, 4, 5, 6, 7, 8, 9, 10 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I19-Small Molecule Single Crystal Diffraction	Interactions of small-molecule guests with interior and exterior surfaces of a coordination cage host Christopher G. P. Taylor , Jennifer S. Train , Michael D. Ward Chemistry 2, 510 - 524 DOI: 10.3390/chemistry2020031 Diamond Proposal Number(s): [19876] Open Access Show Abstract ▼ Abstract: Coordination cages are well-known to act as molecular containers that can bind small-molecule guests in their cavity. Such cavity binding is associated with interactions of the guests with the surrounding set of surfaces that define the cavity; a guest that is a good fit for the cavity will have many favourable interactions with the interior surfaces of the host. As cages have exterior as well as interior surfaces, possibilities also exist for ‘guests’ that are not well-bound in the cavity to interact with the exterior surface of the cage where spatial constraints are fewer. In this paper, we report a combined solid-state and solution study using an octanuclear cubic M8L12 coordination cage which illustrates the occurrence of both types of interaction. Firstly, crystallographic studies show that a range of guests bind inside the cavity (either singly or in stacked pairs) and/or interact with the cage exterior surface, depending on their size. Secondly, fluorescence titrations in aqueous solution show how some flexible aromatic disulfides show two separate types of interaction with the cage, having different spectroscopic consequences; we ascribe this to separate interactions with the exterior surface and the interior surface of the host cage with the former having a higher binding constant. Overall, it is clear that the idea of host/guest interactions in molecular containers needs to take more account of external surface interactions as well as the obvious cavity-based binding.	Jun 2020
B21-High Throughput SAXS I04-Macromolecular Crystallography	Structure, dynamics and cellular insight into novel substrates of the Legionella pneumophila type II secretion system Theo J. Portlock , Jessica Y. Tyson , Sarath C. Dantu , Saima Rehman , Richard C. White , Ian E. Mcintire , Lee Sewell , Katherine Richardson , Rosie Shaw , Alessandro Pandini , Nicholas P. Cianciotto , James Garnett Frontiers In Molecular Biosciences 7 DOI: 10.3389/fmolb.2020.00112 Diamond Proposal Number(s): [7299, 21035] Open Access Show Abstract ▼ Abstract: Legionella pneumophila is a Gram-negative bacterium that is able to replicate within a broad range of aquatic protozoan hosts. L. pneumophila is also an opportunistic human pathogen that can infect macrophages and epithelia in the lung and lead to Legionnaires’ disease. The type II secretion system is a key virulence factor of L. pneumophila and is used to promote bacterial growth at low temperatures, regulate biofilm formation, modulate host responses to infection, facilitate bacterial penetration of mucin gels and is necessary for intracellular growth during the initial stages of infection. The L. pneumophila type II secretion system exports at least 25 substrates out of the bacterium and several of these, including NttA to NttG, contain unique amino acid sequences that are generally not observed outside of the Legionella genus. NttA, NttC, and NttD are required for infection of several amoebal species but it is unclear what influence other novel substrates have within their host. In this study, we show that NttE is required for optimal infection of Acanthamoeba castellanii and Vermamoeba vermiformis amoeba and is essential for the typical colony morphology of L. pneumophila. In addition, we report the atomic structures of NttA, NttC, and NttE and through a combined biophysical and biochemical hypothesis driven approach we propose novel functions for these substrates during infection. This work lays the foundation for future studies into the mechanistic understanding of novel type II substrate functions and how these relate to L. pneumophila ecology and disease.	Jun 2020
I24-Microfocus Macromolecular Crystallography	Crystal structures of human PAICS reveal substrate and product binding of an emerging cancer target Jana Skerlova , Judith Unterlass , Mona Göttmann , Petra Marttila , Evert Homan , Thomas Helleday , Ann-sofie Jemth , Pal Stenmark Journal Of Biological Chemistry DOI: 10.1074/jbc.RA120.013695 Diamond Proposal Number(s): [15806] Show Abstract ▼ Abstract: The bifunctional human enzyme phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazolesuccinocarboxamide synthetase (PAICS) catalyzes two essential steps in the de novo purine biosynthesis pathway. PAICS is overexpressed in many cancers and could be a promising target for the development of cancer therapeutics. Here, using gene knockdowns and clonogenic survival and cell viability assays, we demonstrate that PAICS is required for growth and survival of prostate cancer cells. PAICS catalyzes the carboxylation of aminoimidazole ribonucleotide (AIR) and the subsequent conversion of carboxyaminoimidazole ribonucleotide (CAIR) and L-aspartate to N-succinylcarboxamide-5-aminoimidazole ribonucleotide (SAICAR). Of note, we present the first structures of human octameric PAICS in complexes with native ligands. In particular, we report the structure of PAICS with CAIR bound in the active sites of both domains and SAICAR bound in one of the SAICAR synthetase domains. Moreover, we report the PAICS structure with SAICAR and an ATP analog occupying the SAICAR synthetase active site. These structures provide insight into substrate and product binding and the architecture of the active sites, disclosing important structural information for rational design of PAICS inhibitors as potential anticancer drugs.	Jun 2020
B18-Core EXAFS	Following the formation of silver nanoparticles using in situ x-ray absorption spectroscopy Ian J. Godfrey , Andrew J. Dent , Ivan Parkin , Shinya Maenosono , Gopinathan Sankar Acs Omega DOI: 10.1021/acsomega.0c00697 Diamond Proposal Number(s): [9949] Open Access Show Abstract ▼ Abstract: The formation of silver and Au@Ag core@shell nanoparticles via reduction of AgNO3 by trisodium citrate was followed using in situ X-ray absorption near-edge structure (XANES) spectroscopy and time-resolved UV–visible (UV–vis) spectroscopy. The XANES data were analyzed through linear combination fitting, and the reaction kinetics were found to be consistent with first-order behavior with respect to silver cations. For the Au@Ag nanoparticles, the UV–vis data of a lab-scale reaction showed a gradual shift in dominance between the gold- and silver-localized surface plasmon absorbance bands. Notably, throughout much of the reaction, distinct gold and silver contributions to the UV–vis spectra were observed; however, in the final product, the contributions were not distinct.	Jun 2020
I19-Small Molecule Single Crystal Diffraction	An expandable hydrogen-bonded organic framework characterized by three-dimensional electron diffraction Peng Cui , Erik Svensson Grape , Peter R. Spackman , Yue Wu , Rob Clowes , Graeme M. Day , A. Ken Inge , Marc A. Little , Andrew I. Cooper Journal Of The American Chemical Society DOI: 10.1021/jacs.0c04885 Diamond Proposal Number(s): [23666] Show Abstract ▼ Abstract: A molecular crystal of a 2-D hydrogen-bonded organic framework (HOF) undergoes an unusual structural transformation after solvent removal from the crystal pores during activation. The conformationally flexible host molecule, ABTPA, adapts its molecular conformation during activation to initiate a framework expansion. The microcrystalline activated phase was characterized by three-dimensional electron diffraction (3D ED), which revealed that ABTPA uses out-of-plane anthracene units as adaptive structural anchors. These units change orientation to generate an expanded, lower density framework material in the activated structure. The porous HOF, ABTPA-2, has robust dynamic porosity (SABET = 1183 m2 g-1) and exhibits negative area thermal expansion. We use crystal structure prediction (CSP) to understand the underlying energetics behind the structural transformation and discuss the challenges facing CSP for such flexible molecules.	Jun 2020
B21-High Throughput SAXS	Ethosomes for coenzyme Q10 cutaneous administration: From design to 3D skin tissue evaluation Maddalena Sguizzato , Paolo Mariani , Francesco Spinozzi , Mascia Benedusi , Franco Cervellati , Rita Cortesi , Markus Drechsler , Roxane Prieux , Giuseppe Valacchi , Elisabetta Esposito Antioxidants 9 DOI: 10.3390/antiox9060485 Diamond Proposal Number(s): [21035] Open Access Show Abstract ▼ Abstract: Ethosome represents a smart transdermal vehicle suitable for solubilization and cutaneous application of drugs. Coenzyme Q10 is an endogenous antioxidant whose supplementation can counteract many cutaneous disorders and pathologies. In this respect, the present study describes the production, characterization, and cutaneous protection of phosphatidylcholine based ethosomes as percutaneous delivery systems for coenzyme Q10. CoQ10 entrapment capacity in ethosomes was almost 100%, vesicles showed the typical ‘fingerprint’ structure, while mean diameters were around 270 nm, undergoing an 8% increase after 3 months from production. An ex-vivo study, conducted by transmission electron microscopy, could detect the uptake of ethosomes in human skin fibroblasts and the passage of the vesicles through 3D reconstituted human epidermis. Immunofluorescence analyses were carried on both on fibroblasts and 3D reconstituted human epidermis treated with ethosomes in the presence of H2O2 as oxidative stress challenger, evaluating 4-hydroxynonenal protein adducts which is as a reliable biomarker for oxidative damage. Notably, the pretreatment with CoQ10 loaded in ethosomes exerted a consistent protective effect against oxidative stress, in both models, fibroblasts and in reconstituted human epidermis respectively.	Jun 2020
B22-Multimode InfraRed imaging And Microspectroscopy	Aluminosilicate haloes preserve complex life approximately 800 million years ago Ross P. Anderson , Nicholas J. Tosca , Gianfelice Cinque , Mark D. Frogley , Ioannis Lekkas , Austin Akey , Gareth M. Hughes , Kristin D. Bergmann , Andrew H. Knoll , Derek E. G. Briggs Interface Focus 10 DOI: 10.1098/rsfs.2020.0011 Diamond Proposal Number(s): [15975, 21059] Open Access Show Abstract ▼ Abstract: Mudstone-hosted microfossils are a major component of the Proterozoic fossil record, particularly dominating the record of early eukaryotic life. Early organisms possessed no biomineralized parts to resist decay and controls on their fossilization in mudstones are poorly understood. Consequently, the Proterozoic fossil record is compromised—we do not know whether changing temporal/spatial patterns of microfossil occurrences reflect evolution or the distribution of favourable fossilization conditions. We investigated fossilization within the approximately 1000 Ma Lakhanda Group (Russia) and the approximately 800 Ma Svanbergfjellet and Wynniatt formations (Svalbard and Arctic Canada). Vertical sections of microfossils and surrounding matrices were extracted from thin sections by focused ion beam milling. Elemental mapping and synchrotron-based infrared microspectroscopy revealed that microfossils are surrounded by haloes rich in aluminium, probably hosted in kaolinite. Kaolinite has been implicated in Cambrian Burgess Shale-type (BST) fossilization and is known to slow the growth of degraders. The Neoproterozoic mudstone microfossil record may be biased to tropical settings conducive to kaolinite formation. These deposits lack metazoan fossils even though they share fossilization conditions with younger BST deposits that are capable of preserving non-mineralizing metazoans. Thus metazoans, at least those typically preserved in BST deposits, were probably absent from sedimentary environments before approximately 800 Ma.	Jun 2020
I20-Scanning-X-ray spectroscopy (XAS/XES)	Toward an internally consistent model for Hg(II) chemical speciation calculations in bacterium–natural organic matter–low molecular mass thiol systems Yu Song , Gbotemi A. Adediran , Tao Jiang , Shusaku Hayama , Erik Bjorn , Ulf Skyllberg Environmental Science & Technology DOI: 10.1021/acs.est.0c01751 Diamond Proposal Number(s): [9157] Show Abstract ▼ Abstract: To advance the scientific understanding of bacteria-driven mercury (Hg) transformation processes in natural environments, thermodynamics and kinetics of divalent mercury Hg(II) chemical speciation need to be understood. Based on Hg LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopic information, combined with competitive ligand exchange (CLE) experiments, we determined Hg(II) structures and thermodynamic constants for Hg(II) complexes formed with thiol functional groups in bacterial cell-membranes of two extensively studied Hg(II) methylating bacteria: Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132. The Hg EXAFS data suggest 5% of the total number of membrane thiol functionalities (Mem-RStot = 380 ± 50 µmol g−1 C) are situated closely enough to be involved in a 2-coordinated Hg(Mem-RS)2 structure in Geobacter. The remaining 95% of Mem-RSH are involved in mixed-ligation Hg(II)-complexes, either with low molecular mass (LMM) thiols like Cys, Hg(Cys)(Mem-RS) or with neighboring O/N membrane functionalities, Hg(Mem-RSRO). We report log K values for the formation of the structures Hg(Mem-RS)2, Hg(Cys)(Mem-RS), and Hg(Mem-RSRO) to be 39.1 ± 0.2 , 38.1 ± 0.1 and 25.6 ± 0.1, respectively, for Geobacter; and 39.2 ± 0.2 , 38.2 ± 0.1 and 25.7 ± 0.1, respectively for ND132. Combined with results obtained from previous studies using the same methodology to determine chemical speciation of Hg(II) in presence of natural organic matter (Suwannee River DOM) and 15 LMM thiols, an internally consistent thermodynamic data set is created, which we recommend to be used in studies of Hg transformation processes in Bacterium–NOM–LMM thiols systems.	Jun 2020
B16-Test Beamline	Development of an array of compound refractive lenses for sub-pixel resolution, large field of view, and time-saving in scanning hard X-ray microscopy Talgat Mamyrbayev , Alexander Opolka , Alexey Ershov , Josephine Gutekunst , Pascal Meyer , Katsumasa Ikematsu , Atsushi Momose , Arndt Last Applied Sciences 10 DOI: 10.3390/app10124132 Open Access Show Abstract ▼ Abstract: A two-dimensional array of compound refractive lenses (2D array of CRLs) designed for hard X-ray imaging with a 3.5 mm2 large field of view is presented. The array of CRLs consists of 2D polymer biconcave parabolic 34 × 34 multi-lenses fabricated via deep X-ray lithography. The developed refractive multi-lens array was applied for sub-pixel resolution scanning transmission X–ray microscopy; a raster scan with only 55 × 55 steps provides a 3.5 megapixel image. The optical element was experimentally characterized at the Diamond Light Source at 34 keV. An array of point foci with a 55 µm period and an average size of ca. 2.1 µm × 3.6 µm was achieved. In comparison with the conventional scanning transmission microscopy using one CRL, sub-pixel resolution scanning transmission hard X-ray microscopy enables a large field of view and short scanning time while keeping the high spatial resolution.	Jun 2020
I19-Small Molecule Single Crystal Diffraction	Photochemical unmasking of polyyne rotaxanes Steffen Woltering , Przemyslaw Gawel , Kirsten E. Christensen , Amber L. Thompson , Harry L. Anderson Journal Of The American Chemical Society DOI: 10.1021/jacs.0c05308 Diamond Proposal Number(s): [20876] Show Abstract ▼ Abstract: Bulky photo-labile masked alkyne equivalents (MAEs) are needed for the synthesis of polyyne polyrotaxanes, as insulated molecular wires and as stabilized forms of the linear polymeric allotrope of carbon, carbyne. We have synthesized a novel MAE based on phenanthrene and compared it with an indane-based MAE. Photochemical unmasking of model compounds was studied at different wavelengths (250 nm and 350 nm), and key products were identified by NMR spectroscopy and X-ray crystallography. UV irradiation at 250 nm leads to unmasking of both MAEs. Irradiation of the phenanthrene system at 350 nm results in quantitative dimerization via [2+2] cycloaddition to form a [3]-ladderane; irradiation of this ladderane at 250 nm generates a dihydrotriphenylene, which can be oxidized easily to a triphenylene. Irradiation of the indane-based MAE at 350 nm in the presence of traces of oxygen forms an endoperoxide and a bisepoxide. Both MAEs have been incorporated into rotaxanes via copper-mediated active metal template Glaser or Cadiot-Chodkiewicz coupling. The identity of the rotaxanes was confirmed by NMR spectroscopy and mass spectrometry. The phenanthrene rotaxane decomposes during attempted photochemical unmasking, whereas photolysis of the indane rotaxane results in unmasking of the polyyne thread to form a rotaxane with a chain of 16 sp-hybridized carbon atoms. This approach opens avenues towards the synthesis of encapsulated carbon allotropes.	Jun 2020

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User