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111 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I02-Macromolecular Crystallography I03-Macromolecular Crystallography I04-Macromolecular Crystallography	Design, synthesis and structural analysis of glucocerebrosidase imaging agents Gideon J. Davies , Rhianna J. Rowland , Yurong Chen , Imogen Breen , Liang Wu , Wendy A. Offen , Thomas Beenakker , Qin Su , Adrianus M. C. H. Van Den Nieuwendijk , Johannes M. F. G. Aerts , Marta Artola , Herman S. Overkleeft Chemistry – A European Journal DOI: 10.1002/chem.202102359 Diamond Proposal Number(s): [13587, 18598] Show Abstract ▼ Abstract: Gaucher disease (GD) is a lysosomal storage disorder caused by inherited deficiencies in β-glucocerebrosidase (GBA). Current treatments require rapid disease diagnosis and a means of monitoring therapeutic efficacy, both of which may be supported by the use of GBA-targeting activity-based probes (ABPs). Here, we report the synthesis and structural analysis of a range of cyclophellitol epoxide and aziridine inhibitors and ABPs for GBA. We demonstrate their covalent mechanism-based mode of action and uncover binding of the new N- functionalised aziridines to the ligand binding cleft. These inhibitors became scaffolds for the development of ABPs; the O6-fluorescent tags of which bind in an allosteric site at the dimer interface. Considering GBA’s preference for O6- and N -functionalised reagents, we synthesised a bi-functional aziridine ABP which we hoped would offer a more powerful imaging agent. Whilst this ABP binds to two unique active site clefts of GBA, no further benefit in potency was achieved over our first generation ABPs. Nevertheless, such ABPs should serve useful in the study of GBA in relation to GD and inform the design of future probes.	Sep 2021
I03-Macromolecular Crystallography I04-1-Macromolecular Crystallography (fixed wavelength)	One-step synthesis of photoaffinity probes for live-cell MS-based proteomics David J. Fallon , Stephanie Lehmann , Chun‐wa Chung , Alex Phillipou , Christian Eberl , Ken G. M. Fantom , Francesca Zappacosta , Vipulkumar K. Patel , Marcus Bantscheff , Christopher J. Schofield , Nicholas C. O. Tomkinson , Jacob T. Bush Chemistry – A European Journal 71 DOI: 10.1002/chem.202102036 Diamond Proposal Number(s): [20024] Show Abstract ▼ Abstract: We present a one-step Ugi reaction protocol for the expedient synthesis of photoaffinity probes for live-cell MS-based proteomics. The reaction couples an amine affinity function with commonly used photoreactive groups, and a variety of handle functionalities. Using this technology, a series of pan-BET (BET: bromodomain and extra-terminal domain) selective bromodomain photoaffinity probes were obtained by parallel synthesis. Studies on the effects of photoreactive group, linker length and irradiation wavelength on photocrosslinking efficiency provide valuable insights into photoaffinity probe design. Optimal probes were progressed to MS-based proteomics to capture the BET family of proteins from live cells and reveal their potential on- and off-target profiles.	Sep 2021
I03-Macromolecular Crystallography I04-Macromolecular Crystallography	Iron binding in the ferroxidase site of human mitochondrial ferritin Silvia Ciambellotti , Alessandro Pratesi , Giusy Tassone , Paola Turano , Stefano Mangani , Cecilia Pozzi Chemistry – A European Journal DOI: 10.1002/chem.202102270 Show Abstract ▼ Abstract: Ferritins are nanocage proteins that store iron ions in their central cavity as hydrated ferric oxide biominerals. In mammals, further the L (light) and H (heavy) chains constituting cytoplasmic maxi-ferritins, an additional type of ferritin has been identified, the mitochondrial ferritin (MTF). Human MTF (hMTF) is a functional homopolymeric H-like ferritin performing the ferroxidase activity in its ferroxidase site (FS), in which Fe(II) is oxidized to Fe(III) in the presence of dioxygen. To better investigate its ferroxidase properties, here we performed time-lapse X-ray crystallography analysis of hMTF, providing structural evidence of how iron ions interact with hMTF and of their binding to the FS. Transient iron binding sites, populating the pathway along the cage from the iron entry channel to the catalytic center, were also identified. Furthermore, our kinetic data at variable iron loads indicate that the catalytic iron oxidation reaction occurs via a diferric peroxo intermediate followed by the formation of ferric-oxo species, with significant differences with respect to human H-type ferritin.	Aug 2021
I19-Small Molecule Single Crystal Diffraction	Enantioselective recognition of racemic amino alcohols in aqueous solution by chiral metal-oxide keplerate {Mo132}-cluster capsules Lee Cronin , Robert Pow , Zoe Sinclair , Nicola Bell , Nancy Watfa , Yousef Abul-Haija , Deliang Long Chemistry – A European Journal DOI: 10.1002/chem.202100899 Diamond Proposal Number(s): [18953] Open Access Show Abstract ▼ Abstract: Determining the relative configuration or enantiomeric excess of a substance may be achieved using NMR spectroscopy by employing chiral shift reagents (CSRs). Such reagents non-covalently interact with the chiral solute, resulting in each chiral form experiencing different magnetic anisotropy, which is reflected in their NMR spectra. The Keplerate polyoxometalate (POM) is a molybdenum-based, water-soluble, discrete inorganic structure with a pore-accessible inner cavity, decorated by differentiable ligands. Through ligand exchange from the self-assembled nanostructure we have synthesized a set of chiral Keplerate host molecules. By exploiting interactions of analyte molecules at the surface pores we establish the relative configuration of chiral amino alcohol guests (phenylalaninol and 2-amino-1-phenylethanol) in aqueous solvent and determine their enantiomeric excess by 1 H NMR. The use of POMs as chiral shift reagents represents an application of the class that is yet to be well established and opens avenues into aqueous host-guest chemistry with self-assembled recognition agents.	Jul 2021
I11-High Resolution Powder Diffraction	Cation ordering and exsolution in copper‐containing forms of the flexible zeolite Rho (Cu,M‐Rho; M = H, Na) and their consequences for CO2 adsorption Magdalena Lozinska , Sophie Jamieson , Maarten Verbraeken , David Miller , Bela Bode , Claire Murray , Stefano Brandani , Paul Anthony Wright Chemistry – A European Journal DOI: 10.1002/chem.202101664 Diamond Proposal Number(s): [22322] Show Abstract ▼ Abstract: The flexibility of the zeolite Rho framework offers great potential for tunable molecular sieving. The fully copper-exchanged form of Rho and mixed Cu,H- and Cu,Na-forms have been prepared. EPR spectroscopy reveals Cu 2+ cations are present in the dehydrated forms and Rietveld refinement shows these prefer S6R sites, away from the d8r windows that control diffusion. Fully exchanged Cu-Rho remains in an open form upon dehydration, the d8r windows remain nearly circular and the occupancy of window sites is low, so that it adsorbs CO 2 rapidly at room temperature. Breakthrough tests with 10% CO 2 /40% CH 4 mixtures show that Cu 4.9 -Rho is able to produce pure methane, albeit with a relatively low capacity at this p CO2 due to the weak interaction of CO 2 with Cu cations. This is in strong contrast with Na-Rho, where cations in narrow elliptical window sites enable CO 2 to be adsorbed with high selectivity and uptake but too slowly to enable the production of pure methane in similar breakthrough experiments. A series of Cu,Na-Rho materials was prepared to improve uptake and selectivity compared to Cu-Rho, and kinetics compared to Na-Rho. Remarkably, Cu,Na-Rho with >2 Cu cations per unit cell exhibited exsolution, due to the preference of Na cations for narrow S8R sites in distorted Rho and of Cu cations for S6R sites in the centric, open form of Rho. The exsolved Cu,Na-Rho showed improved performance in CO 2 /CH 4 breakthrough tests, producing pure CH 4 with improved uptake and CO 2 /CH 4 selectivity compared to that of Cu 4.9 -Rho.	Jul 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Monitoring the structure evolution of titanium oxide photocatalysts: From the molecular form via the amorphous state to the crystalline phase Ezgi Onur Sahin , Yitao Dai , Candace Chan , Harun Tuysuz , Wolfgang Schmidt , Joohyun Lim , Siyuan Zhang , Cristina Scheu , Claudia Weidenthaler Chemistry – A European Journal DOI: 10.1002/chem.202101117 Diamond Proposal Number(s): [12102] Show Abstract ▼ Abstract: Amorphous TixOy with high surface area has attracted significant interest as photocatalyst with higher activity in ultraviolet (UV) light-induced water splitting applications compared to commercial nanocrystalline TiO2. Under photocatalytic operation conditions, the structure of the molecular titanium alkoxide precursor rearranges upon hydrolysis and leads to higher connectivity of the structure-building units. Structurally ordered domains with sizes smaller than 7 Å form larger aggregates. The experimental scattering data can be explained best with a structure model consisting of an anatase-like core and a distorted shell. Upon exposure with UV light, the white TixOy suspension turns dark corresponding to the reduction of Ti 4+ to Ti 3+ as confirmed by electron energy loss spectroscopy (EELS). Heat-induced crystallisation was followed by in situ temperature-dependent total scattering experiments. First, ordering in the Ti-O environment takes place upon to 350 °C. Above this temperature, the distorted anatase core starts to grow but the structure obtained at 400 °C is still not fully ordered.	Jun 2021
B18-Core EXAFS E01-JEM ARM 200CF I11-High Resolution Powder Diffraction	Direct visualization of substitutional Li doping in supported Pt nanoparticles and their ultra-selective catalytic hydrogenation performance Tianyi Chen , Christopher Foo , Jianwei Zheng , Huihuang Fang , Peter Nellist , Edman Shik Chi Tsang Chemistry – A European Journal DOI: 10.1002/chem.202101470 Diamond Proposal Number(s): [20856] Show Abstract ▼ Abstract: It has only recently been established that doping light elements (lithium, boron, and carbon) into supported transition metals can fill interstitial sites, which can be observed by the expanded unit cell. As an example, interstitial lithium (intLi) can block H filling octahedral interstices of palladium metal lattice, which improves partial hydrogenation of alkynes to alkenes under hydrogen. In contrast, herein, we report intLi is not found in the case of Pt/C. Instead, we observe for the first time a direct ‘substitution’ of Pt with substitutional lithium (subLi) in alternating atomic columns using scanning transmission electron microscopy-annular dark field (STEM-ADF). This ordered substitutional doping results in a contraction of the unit cell as shown by high-quality synchrotron X-ray diffraction (SXRD). The electron donation of d-band of Pt without higher orbital hybridizations by subLi offers an alternative way for ultra-selectivity in catalytic hydrogenation of carbonyl compounds by suppressing the facile CO bond breakage that would form alcohols.	Jun 2021
I09-Surface and Interface Structural Analysis	Structural transformation of surface-confined porphyrin networks by addition of Co atoms Brian David Baker Cortés , Mihaela Enache , Kathrin Küster , Florian Studener , Tien-Lin Lee , Nicolas Marets , Véronique Bulach , Mir Wais Hosseini , Meike Stohr Chemistry – A European Journal DOI: 10.1002/chem.202101217 Diamond Proposal Number(s): [11841] Show Abstract ▼ Abstract: The self-assembly of a nickel-porphyrin derivative (Ni-DPPyP) containing two pyridyl coordinating sites and two pentyl chains at trans meso positions was studied with scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) on Au(111). Deposition of Ni-DPPyP onto Au(111) gave rise to a close-packed network for coverages smaller or equal to one monolayer as revealed by STM and LEED. The molecular arrangement of this two-dimensional network is stabilized via hydrogen bonds formed between the pyridyl’s nitrogen and hydrogen atoms from the pyrrole groups of neighboring molecules. Subsequent deposition of cobalt atoms onto the close-packed network and post-deposition annealing at 423 K led to the formation of a Co-coordinated hexagonal porous network. As confirmed by XPS measurements, the porous network is stabilized by metal-ligand interactions between one cobalt atom and three pyridyl ligands, each pyridyl ligand coming from a different Ni-DPPyP molecule.	Jun 2021
I04-Macromolecular Crystallography	The development of non‐hydrolysable oligosaccharide activity‐based inactivators for endoglycanases: A case study on a‐1,6 mannanases Hermen S. Overkleeft , Sybrin Schröder , Wendy Offen , Alexandra Males , Yi Jin , Casper De Boer , Jacopo Enotarpi , Gijs Van Der Marel , Bogdan Florea , Jeroen Codée , Gideon Davies Chemistry – A European Journal DOI: 10.1002/chem.202101255 Diamond Proposal Number(s): [13587, 18598] Show Abstract ▼ Abstract: There is a vast genomic resource for enzymes active on carbohydrates. Lagging far behind, however, are functional chemical tools for the rapid characterization of carbohydrate‐active enzymes. Activity‐based probes (ABPs) offer one chemical solution to these issues with ABPs based upon cyclophellitol epoxide and aziridine covalent and irreversible inhibitors representing a potent and widespread approach. Such inhibitors for enzymes active on polysaccharides are potentially limited by the requirement for several glycosidic bonds, themselves substrates for the enzyme targets. Here we show that non‐hydrolysable trisaccharide can be synthesized and applied even to enzymes with challenging subsite requirements. We find that incorporation of carbasugar moieties, which we accomplished by cuprate‐assisted regioselective trans‐diaxial epoxide opening of carba‐mannal we synthesised for this purpose, yields inactivators that act as powerful activity‐based inhibitors for a‐1,6 endo‐mannanases. 3‐D structures at 1.35 – 1.47 Å resolutions confirm the design rationale and binding to the enzymatic nucleophile. Carbasugar oligosaccharide cyclophellitols offer a powerful new approach for the design of robust endoglycosidase inhibitors, while the synthesis procedures presented here should allow adaptation towards activity‐based endoglycosidase probes as well as configurational isosteres targeting other endoglycosidase families.	Apr 2021
I11-High Resolution Powder Diffraction I19-Small Molecule Single Crystal Diffraction	Inherent ethyl acetate selectivity in a trianglimine molecular solid Donglin He , Chengxi Zhao , Linjiang Chen , Marc Little , Samantha Chong , Rob Clowes , Katherine Mckie , Mark Roper , Graeme Day , Ming Liu , Andrew Cooper Chemistry – A European Journal DOI: 10.1002/chem.202101510 Diamond Proposal Number(s): [21726, 17193] Show Abstract ▼ Abstract: Ethyl acetate is an important chemical raw material and solvent. It is also a key volatile organic compound in the brewing industry and a marker for lung cancer. Materials that are highly selective toward ethyl acetate are needed for its separation and detection. Here, we report a trianglimine macrocycle ( TAMC ) that selectively adsorbs ethyl acetate by forming a solvate. Crystal structure prediction showed this to be the lowest energy solvate structure available. This solvate leaves a metastable, ‘templated’ cavity after solvent removal. Adsorption and breakthrough experiments confirmed that imprinted TAMC has adequate adsorption kinetics to separate ethyl acetate from azeotropic mixtures with ethanol, which is a challenging and energy‐intensive industrial separation.	Apr 2021

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