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27 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3 [Next/Last]

Instruments / Technical Area	Publication Details	Published
B23-Circular Dichroism	Mueller matrix polarimetry on cyanine dye J-aggregates Samuel R. Clowes , Dora M. Răsădean , Tiberiu-M. Gianga , Tamas Javorfi , Rohanah Hussain , Giuliano Siligardi , G. Dan Pantos Molecules 28 DOI: 10.3390/molecules28041523 Diamond Proposal Number(s): [29075, 31797] Open Access Show Abstract ▼ Abstract: Cyanine dyes are known to form H- and J-aggregates in aqueous solutions. Here we show that the cyanine dye, S0271, assembles in water into vortex induced chiral J-aggregates. The chirality of the J-aggregates depends on the directionality of the vortex. This study utilised both conventional benchtop CD spectropolarimeters and Mueller matrix polarimetry. It was found that J-aggregates have real chirality alongside linear dichroism and linear and circular birefringence. We identify the factors that are key to the formation of metastable chiral J-aggregates and propose a mechanism for their assembly.	Feb 2023
	Variable temperature behaviour of the hybrid double perovskite MA2KBiCl6 Fengxia Wei , Yue Wu , Shijing Sun , Zeyu Deng , Li Tian Chew , Baisong Cheng , Cheng Cheh Tan , Timothy J. White , Anthony K. Cheetham Molecules 28 DOI: 10.3390/molecules28010174 Open Access Show Abstract ▼ Abstract: Perovskite-related materials show very promising properties in many fields. Pb-free perovskites are particularly interesting, because of the toxicity of Pb. In this study, hybrid double perovskite MA2KBiCl6 (MA = methylammonium cation) was found to have interesting variable temperature behaviours. Both variable temperature single crystal X-ray diffraction, synchrotron powder diffraction, and Raman spectroscopy were conducted to reveal a rhombohedral to cubic phase transition at around 330 K and an order to disorder transition for inorganic cage below 210 K.	Dec 2022
I24-Microfocus Macromolecular Crystallography	Discovery and characterization of a cryptic secondary binding site in the molecular chaperone HSP70 Suzanne O'Connor , Yann-Vai Le Bihan , Isaac M. Westwood , Manjuan Liu , Oi Wei Mak , Gabriel Zazeri , Ana P. R. Povinelli , Alan M. Jones , Rob Van Montfort , Jóhannes Reynisson , Ian Collins Molecules 27 DOI: 10.3390/molecules27030817 Diamond Proposal Number(s): [6385] Open Access Show Abstract ▼ Abstract: Heat Shock Protein 70s (HSP70s) are key molecular chaperones that are overexpressed in many cancers and often associated with metastasis and poor prognosis. It has proven difficult to develop ATP-competitive, drug-like small molecule inhibitors of HSP70s due to the flexible and hydrophilic nature of the HSP70 ATP-binding site and its high affinity for endogenous nucleotides. The aim of this study was to explore the potential for the inhibition of HSP70 through alternative binding sites using fragment-based approaches. A surface plasmon resonance (SPR) fragment screen designed to detect secondary binding sites in HSP70 led to the identification by X-ray crystallography of a cryptic binding site in the nucleotide-binding domain (NBD) of HSP70 adjacent to the ATP-binding site. Fragment binding was confirmed and characterized as ATP-competitive using SPR and ligand-observed NMR methods. Molecular dynamics simulations were applied to understand the interactions with the protein upon ligand binding, and local secondary structure changes consistent with interconversion between the observed crystal structures with and without the cryptic pocket were detected. A virtual high-throughput screen (vHTS) against the cryptic pocket was conducted, and five compounds with diverse chemical scaffolds were confirmed to bind to HSP70 with micromolar affinity by SPR. These results identified and characterized a new targetable site on HSP70. While targeting HSP70 remains challenging, the new site may provide opportunities to develop allosteric ATP-competitive inhibitors with differentiated physicochemical properties from current series.	Jan 2022
I11-High Resolution Powder Diffraction	The impact of redox, hydrolysis and dehydration chemistry on the structural and magnetic properties of magnetoferritin prepared in variable thermal conditions Lucia Balejčíková , Karel Saksl , Jozef Kováč , Anne Martel , Vasil M. Garamus , Mikhail V. Avdeev , Viktor I. Petrenko , László Almásy , Peter Kopčanský Molecules 26 DOI: 10.3390/molecules26226960 Diamond Proposal Number(s): [17415] Open Access Show Abstract ▼ Abstract: Ferritin, a spherically shaped protein complex, is responsible for iron storage in bacteria, plants, animals, and humans. Various ferritin iron core compositions in organisms are associated with specific living requirements, health state, and different biochemical roles of ferritin isomers. Magnetoferritin, a synthetic ferritin derivative, serves as an artificial model system of unusual iron phase structures found in humans. We present the results of a complex structural study of magnetoferritins prepared by controlled in vitro synthesis. Using various complementary methods, it was observed that manipulation of the synthesis technology can improve the physicochemical parameters of the system, which is useful in applications. Thus, a higher synthesis temperature leads to an increase in magnetization due to the formation of the magnetite phase. An increase in the iron loading factor has a more pronounced impact on the protein shell structure in comparison with the pH of the aqueous medium. On the other hand, a higher loading factor at physiological temperature enhances the formation of an amorphous phase instead of magnetite crystallization. It was confirmed that the iron-overloading effect alone (observed during pathological events) cannot contribute to the formation of magnetite.	Nov 2021
I02-Macromolecular Crystallography I03-Macromolecular Crystallography	Crystal structure-guided design of bisubstrate inhibitors and photoluminescent probes for protein kinases of the PIM family Olivier E. Nonga , Darja Lavogina , Erki Enkvist , Katrin Kestav , Apirat Chaikuad , Sarah E. Dixon-Clarke , Alex N. Bullock , Sergei Kopanchuk , Taavi Ivan , Ramesh Ekambaram , Kaido Viht , Stefan Knapp , Asko Uri Molecules 26 DOI: 10.3390/molecules26144353 Diamond Proposal Number(s): [8421] Open Access Show Abstract ▼ Abstract: We performed an X-ray crystallographic study of complexes of protein kinase PIM-1 with three inhibitors comprising an adenosine mimetic moiety, a linker, and a peptide-mimetic (d-Arg)6 fragment. Guided by the structural models, simplified chemical structures with a reduced number of polar groups and chiral centers were designed. The developed inhibitors retained low-nanomolar potency and possessed remarkable selectivity toward the PIM kinases. The new inhibitors were derivatized with biotin or fluorescent dye Cy5 and then applied for the detection of PIM kinases in biochemical solutions and in complex biological samples. The sandwich assay utilizing a PIM-2-selective detection antibody featured a low limit of quantification (44 pg of active recombinant PIM-2). Fluorescent probes were efficiently taken up by U2OS cells and showed a high extent of co-localization with PIM-1 fused with a fluorescent protein. Overall, the developed inhibitors and derivatives represent versatile chemical tools for studying PIM function in cellular systems in normal and disease physiology.	Jul 2021
I19-Small Molecule Single Crystal Diffraction	[CrIII8NiII6]n+ heterometallic coordination cubes Helen M. O’connor , Sergio Sanz , Aaron J. Scott , Mateusz B. Pitak , Wim T. Klooster , Simon J. Coles , Nicholas F. Chilton , Eric J. L. Mcinnes , Paul J. Lusby , Høgni Weihe , Stergios Piligkos , Euan K. Brechin Molecules 26 DOI: 10.3390/molecules26030757 Diamond Proposal Number(s): [11238] Open Access Show Abstract ▼ Abstract: Three new heterometallic [CrIII8NiII6] coordination cubes of formulae [CrIII8NiII6L24(H2O)12](NO3)12 (1), [CrIII8NiII6L24(MeCN)7(H2O)5](ClO4)12 (2), and [CrIII8NiII6L24Cl12] (3) (where HL = 1-(4-pyridyl)butane-1,3-dione), were synthesised using the paramagnetic metalloligand [CrIIIL3] and the corresponding NiII salt. The magnetic skeleton of each capsule describes a face-centred cube in which the eight CrIII and six NiII ions occupy the eight vertices and six faces of the structure, respectively. Direct current magnetic susceptibility measurements on (1) reveal weak ferromagnetic interactions between the CrIII and NiII ions, with JCr-Ni = + 0.045 cm−1. EPR spectra are consistent with weak exchange, being dominated by the zero-field splitting of the CrIII ions. Excluding wheel-like structures, examples of large heterometallic clusters containing both CrIII and NiII ions are rather rare, and we demonstrate that the use of metalloligands with predictable bonding modes allows for a modular approach to building families of related polymetallic complexes. Compounds (1)–(3) join the previously published, structurally related family of [MIII8MII6] cubes, where MIII = Cr, Fe and MII = Cu, Co, Mn, Pd.	Feb 2021
I04-1-Macromolecular Crystallography (fixed wavelength)	How to separate kinase inhibition from undesired monoamine oxidase a inhibition—the development of the DYRK1A inhibitor AnnH75 from the alkaloid harmine Anne Wurzlbauer , Katharina Rüben , Ece Gürdal , Apirat Chaikuad , Stefan Knapp , Wolfgang Sippl , Walter Becker , Franz Bracher Molecules 25 DOI: 10.3390/molecules25245962 Open Access Show Abstract ▼ Abstract: The β-carboline alkaloid harmine is a potent DYRK1A inhibitor, but suffers from undesired potent inhibition of MAO-A, which strongly limits its application. We synthesized more than 60 analogues of harmine, either by direct modification of the alkaloid or by de novo synthesis of β-carboline and related scaffolds aimed at learning about structure–activity relationships for inhibition of both DYRK1A and MAO-A, with the ultimate goal of separating desired DYRK1A inhibition from undesired MAO-A inhibition. Based on evidence from published crystal structures of harmine bound to each of these enzymes, we performed systematic structure modifications of harmine yielding DYRK1A-selective inhibitors characterized by small polar substituents at N-9 (which preserve DYRK1A inhibition and eliminate MAO-A inhibition) and beneficial residues at C-1 (methyl or chlorine). The top compound AnnH75 remains a potent DYRK1A inhibitor, and it is devoid of MAO-A inhibition. Its binding mode to DYRK1A was elucidated by crystal structure analysis, and docking experiments provided additional insights for this attractive series of DYRK1A and MAO-A inhibitors.	Dec 2020
B23-Circular Dichroism	Mapping the chiroptical properties of local domains in thin films of chiral silicon phthalocyanines by CD imaging Dora-Maria Rasadean , Tiberiu-Marius Gianga , Tamas Javorfi , Rohanah Hussain , Giuliano Siligardi , G. Dan Pantos Molecules 25 DOI: 10.3390/molecules25246048 Diamond Proposal Number(s): [23955, 20441, 26447] Open Access Show Abstract ▼ Abstract: The first example of uniformly chiral thin films of silicon phthalocyanines (SiPcs) are reported. The local domains of the films are mapped using circular dichroism (CD) imaging (CDi) technique available at the Diamond B23 beamline. The CDi allowed us to increase the spatial resolution up to 525× when compared with benchtop spectrometers. The results indicate formation on-surface of chiral and stable supramolecular assemblies with homogenous distribution. Chemical functionalization and solvent choice for deposition allow controllable chiroptical properties to be obtained. The method and technique reported in this work could be applied to prepare and characterize a wide variety of chiral thin films.	Dec 2020
B18-Core EXAFS	Understanding the deactivation phenomena of small-pore Mo/H-SSZ-13 during methane dehydroaromatisation Miren Agote-Aran , Anna B. Kroner , David S. Wragg , Wojciech A. Sławiński , Martha Briceno , Husn U. Islam , Igor V. Sazanovich , María E. Rivas , Andrew W. J. Smith , Paul Collier , Ines Lezcano-Gonzalez , Andrew M. Beale Molecules 25 DOI: 10.3390/molecules25215048 Diamond Proposal Number(s): [11623] Open Access Show Abstract ▼ Abstract: Small pore zeolites have shown great potential in a number of catalytic reactions. While Mo-containing medium pore zeolites have been widely studied for methane dehydroaromatisation (MDA), the use of small pore supports has drawn limited attention due to the fast deactivation of the catalyst. This work investigates the structure of the small pore Mo/H-SSZ-13 during catalyst preparation and reaction by operando X-ray absorption spectroscopy (XAS), in situ synchrotron powder diffraction (SPD), and electron microscopy; then, the results are compared with the medium pore Mo/H-ZSM-5. While SPD suggests that during catalyst preparation, part of the MoOx anchors inside the pores, Mo dispersion and subsequent ion exchange was less effective in the small pore catalyst, resulting in the formation of mesopores and Al2(MOO4)3 particles. Unlike Mo/H-ZSM-5, part of the Mo species in Mo/H-SSZ-13 undergoes full reduction to Mo0 during MDA, whereas characterisation of the spent catalyst indicates that differences also exist in the nature of the formed carbon deposits. Hence, the different Mo speciation and the low performance on small pore zeolites can be attributed to mesopores formation during calcination and the ineffective ion exchange into well dispersed Mo-oxo sites. The results open the scope for the optimisation of synthetic routes to explore the potential of small pore topologies.	Nov 2020
B21-High Throughput SAXS	Design of nanosystems for the delivery of quorum sensing inhibitors: A preliminary study Supandeep Singh Hallan , Paolo Marchetti , Daria Bortolotti , Maddalena Sguizzato , Elisabetta Esposito , Paolo Mariani , Claudio Trapella , Roberta Rizzo , Rita Cortesi Molecules 25 DOI: 10.3390/molecules25235655 Diamond Proposal Number(s): [21035] Open Access Show Abstract ▼ Abstract: Biofilm production is regulated by the Quorum Sensing system. Nowadays, Quorum Sensing represents an appealing target to design new compounds to increase antibiotics effects and avoid development of antibiotics multiresistance. In this research the use of liposomes to target two novel synthetic biofilm inhibitors is presented, focusing on a preformulation study to select a liposome composition for in vitro test. Five different liposome (LP) formulations, composed of phosphatidyl choline, cholesterol and charged surfactant (2:1:1, molar ratio) have been prepared by direct hydration and extrusion. As charged surfactants dicetyl phosphate didecyldimethylammonium chloride, di isobutyl phenoxy ethyl dimethyl benzyl ammonium chloride and stearylamine (SA) and have been used. Liposome charge, size and morphology were investigated by zeta potential, photon correlation spectroscopy, small angle x-ray spectroscopy and electron microscopy. LP-SA was selected for the loading of biofilm inhibitors and subjected to high performance liquid chromatography for entrapment capacity evaluation. LP-SA loaded inhibitors showed a higher diameter (223.6 nm) as compared to unloaded ones (205.7 nm) and a dose-dependent anti-biofilm effect mainly after 48 h of treatment, while free biofilm inhibitors loose activity. In conclusion, our data supported the use of liposomes as a strategy to enhance biofilm inhibitors effect.	Nov 2020

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