I03-Macromolecular Crystallography
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Arathy
Jose
,
Daniel
Guest
,
Remi
Legay
,
Graham J.
Tizzard
,
Simon
Coles
,
Mariliza
Derveni
,
Edward
Wright
,
Lester
Marrison
,
Alpha A.
Lee
,
Aaron
Morris
,
Matt
Robinson
,
Frank
Von Delft
,
Daren
Fearon
,
Lizbe
Koekemoer
,
Tetiana
Matviuk
,
Anthony
Aimon
,
Christopher J.
Schofield
,
Tika R.
Malla
,
Nir
London
,
Barnaby W.
Greenland
,
Mark C.
Bagley
,
John
Spencer
Diamond Proposal Number(s):
[19301]
Open Access
Abstract: The pentafluorosulfanyl (-SF5) functional group is of increasing interest as a bioisostere in medicinal chemistry. A library of SF5-containing compounds, including amide, isoxazole, and oxindole derivatives, was synthesised using a range of solution-based and solventless methods, including microwave and ball-mill techniques. The library was tested against targets including human dihydroorotate dehydrogenase (HDHODH). A subsequent focused approach led to synthesis of analogues of the clinically used disease modifying anti-rheumatic drugs (DMARDs), Teriflunomide and Leflunomide, considered for potential COVID-19 use, where SF5 bioisostere deployment led to improved inhibition of HDHODH compared with the parent drugs. The results demonstrate the utility of the SF5 group in medicinal chemistry.
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Feb 2022
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Abstract: The two SARS-CoV-2 proteases, i.e. the main protease (M pro ) and the papain-like protease (PL pro ), which hydrolyze the viral polypeptide chain giving functional non-structural proteins, are essential for viral replication and are medicinal chemistry targets. We report a high-throughput mass spectrometry (MS)-based assay which directly monitors PL pro catalysis in vitro . The assay was applied to investigate the effect of reported small-molecule PL pro inhibitors and selected M pro inhibitors on PL pro catalysis. The results reveal that some, but not all, PL pro inhibitor potencies differ substantially from those obtained using fluorescence-based assays. Some substrate-competing M pro inhibitors, notably PF-07321332 (nirmatrelvir) which is in clinical development, do not inhibit PL pro . Less selective M pro inhibitors, e.g. auranofin, inhibit PL pro , highlighting the potential for dual PL pro /M pro inhibition. MS-based PL pro assays, which are orthogonal to widely employed fluorescence-based assays, are of utility in validating inhibitor potencies, especially for inhibitors operating by non-covalent mechanisms.
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Jan 2022
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I04-Macromolecular Crystallography
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Federica
Verdirosa
,
Laurent
Gavara
,
Laurent
Sevaille
,
Giusy
Tassone
,
Giuseppina
Corsica
,
Alice
Legru
,
Georges
Feller
,
Giulia
Chelini
,
Paola S.
Mercuri
,
Silvia
Tanfoni
,
Filomena
Sannio
,
Manuela
Benvenuti
,
Giulia
Cerboni
,
Filomena
De Luca
,
Ezeddine
Bouajila
,
Yen
Vo Hoang
,
Patricia
Licznar-Fajardo
,
Moreno
Galleni
,
Cecilia
Pozzi
,
Stefano
Mangani
,
Jean-Denis
Docquier
,
Jean-François
Hernandez
Diamond Proposal Number(s):
[21741]
Abstract: Metallo-β-lactamases (MBLs) are increasingly involved as a major mechanism of resistance to carbapenems in relevant opportunistic Gram-negative pathogens. Unfortunately, clinically efficient MBL inhibitors still represent an unmet medical need . We previously reported several series of compounds based on the 1,2,4-triazole-3-thione scaffold. In particular, Schiff bases formed between diversely 5-substituted-4-amino compounds and 2-carboxybenzaldehyde were broad-spectrum inhibitors of VIM-type, NDM-1 and IMP-1 MBLs. Unfortunately, they were unable to restore antibiotic susceptibility of MBL-producing bacteria, probably because of poor penetration and/or susceptibility to hydrolysis. To improve their microbiological activity, we developed compounds where the hydrazone-like bond of the Schiff bases was replaced by a stable ethyl link. This small change resulted in a narrower inhibition spectrum, as all compounds were poorly or not inhibiting NDM-1 and IMP-1, but some showed a significantly better activity on VIM-type enzymes, with K i values in the μM to sub-μM range. The resolution of the crystallographic structure of VIM-2 in complex with one inhibitor yielded valuable information about their binding mode. Interestingly, several compounds were shown to restore the β-lactam susceptibility of K. pneumoniae clinical isolates. In addition, selected compounds were found to be devoid of toxicity toward human cells at high concentration, thus showing promising safety.
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Jan 2022
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I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[18069]
Open Access
Abstract: Human prolyl‐hydroxylases (PHDs) are hypoxia‐sensing 2‐oxoglutarate (2OG) oxygenases, catalysis by which suppresses the transcription of hypoxia‐inducible factor target genes. PHD inhibition enables the treatment of anaemia/ischaemia‐related disease. The PHD inhibitor Molidustat is approved for the treatment of renal anaemia; it differs from other approved/late‐stage PHD inhibitors in lacking a glycinamide side chain. The first reported crystal structures of Molidustat and IOX4 (a brain‐penetrating derivative) complexed with PHD2 reveal how their contiguous triazole, pyrazolone and pyrimidine/pyridine rings bind at the active site. The inhibitors bind to the active‐site metal in a bidentate manner through their pyrazolone and pyrimidine nitrogens, with the triazole π‐π‐stacking with Tyr303 in the 2OG binding pocket. Comparison of the new structures with other PHD inhibitor complexes reveals differences in the conformations of Tyr303, Tyr310, and a mobile loop linking β2–β3, which are involved in dynamic substrate binding/product release.
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Apr 2021
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Krios I-Titan Krios I at Diamond
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Open Access
Abstract: The biogenic formation of hemozoin crystals, a crucial process in heme detoxification by the malaria parasite, is reviewed as an antimalarial drug target. We first focus on the in‐vivo formation of hemozoin. A model is presented, based on native‐contrast 3D imaging obtained by X‐ray and electron microscopy, that hemozoin nucleates at the inner membrane leaflet of the parasitic digestive vacuole, and grows in the adjacent aqueous medium. Having observed quantities of hemoglobin and hemozoin in the digestive vacuole, we present a model that heme liberation from hemoglobin and hemozoin formation is an assembly‐line process. The crystallization is preceded by reaction between heme monomers yielding hematin dimers involving fewer types of isomers than in synthetic hemozoin; this is indicative of protein‐induced dimerization. Models of antimalarial drugs binding onto hemozoin surfaces are reviewed. This is followed by a description of bromoquine, a chloroquine drug analogue, capping a significant fraction of hemozoin surfaces within the digestive vacuole and accumulation of the drug, presumably a bromoquine–hematin complex, at the vacuole's membrane.
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Mar 2021
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I04-1-Macromolecular Crystallography (fixed wavelength)
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Raysa
Khan Tareque
,
Storm
Hassell-Hart
,
Tobias
Krojer
,
Anthony
Bradley
,
Srikannathasan
Velupillai
,
Romain
Talon
,
Michael
Fairhead
,
Iain J.
Day
,
Kamlesh
Bala
,
Robert
Felix
,
Paul D.
Kemmitt
,
Paul
Brennan
,
Frank
Von Delft
,
Laura
Diaz Saez
,
Kilian
Huber
,
John
Spencer
Diamond Proposal Number(s):
[18145]
Abstract: Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium‐throughput X‐ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho‐arylation of 2‐phenylpyridine gave five products resulting from mono‐ and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified.
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Aug 2020
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I24-Microfocus Macromolecular Crystallography
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Diamond Proposal Number(s):
[20221]
Abstract: Diphenylene iodonium (DPI) is known for its inhibitory activities against many flavin‐ and heme‐dependent enzymes and is often used as an NADPH oxidase inhibitor. We probed the efficacy of DPI on two well‐known drug targets, the human monoamine oxidases MAO A and B. UV‐visible spectrophotometry and steady‐state kinetics experiments demonstrate that DPI acts as a competitive MAO inhibitor with Ki values of 1.7 µM and 0.3 µM for MAO A and MAO B, respectively. Elucidation of the crystal structure of human MAO B bound to the inhibitor revealed that DPI binds deeply in the active‐site cavity to establish multiple hydrophobic interactions with the surrounding side chains and the flavin. These data prove that DPI is a genuine MAO inhibitor and the inhibition mechanism does not involve a reaction with the reduced flavin. This binding and inhibitory activity against MAOs, two major ROS‐producing enzymes, will have to be carefully considered when interpreting experiments that rely on DPI for target validation and chemical biology studies on ROS functions.
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May 2020
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I24-Microfocus Macromolecular Crystallography
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Open Access
Abstract: The demand for allosteric targeting of nuclear receptors is high, but examples are limited, and structural information is scarce. The retinoic acid‐related orphan receptor gamma t (RORγt) is an important transcriptional regulator for the differentiation of T helper 17 cells for which the first, and some of the most promising, examples of allosteric nuclear receptor modulation have been reported and structurally proven. In a 2015 patent, filed by the pharmaceutical company Glenmark, a new class of small molecules was reported that act as potent inverse agonists for RORγt. A compound library around the central thienopyrazole scaffold captured a clear structure‐activity relationship, but the binding mechanism of this new class of RORγt modulators has not been elucidated. Using a combination of biochemical and X‐ray crystallography studies, here the allosteric mechanism for the inverse agonism for the most potent compound, classified in the patent as “example 13”, is reported, providing a strongly desired additional example of allosteric nuclear receptor targeting.
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Feb 2020
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I03-Macromolecular Crystallography
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James P.
Holt‐martyn
,
Rasheduzzaman
Chowdhury
,
Anthony
Tumber
,
Tzu‐lan
Yeh
,
Martine I.
Abboud
,
Kerstin
Lippl
,
Christopher T.
Lohans
,
Gareth W.
Langley
,
William
Figg
,
Michael A.
Mcdonough
,
Christopher W.
Pugh
,
Peter J.
Ratcliffe
,
Christopher J.
Schofield
Open Access
Abstract: The 2‐oxoglutarate‐dependent hypoxia inducible factor prolyl hydroxylases (PHDs) are targets for treatment of a variety of diseases including anaemia. One PHD inhibitor is approved for use for the treatment of renal anaemia and others are in late stage clinical trials. The number of reported templates for PHD inhibition is limited. We report structure–activity relationship and crystallographic studies on a promising class of 4‐hydroxypyrimidine‐containing PHD inhibitors.
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Dec 2019
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I03-Macromolecular Crystallography
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Diamond Proposal Number(s):
[16609]
Abstract: Overexpression of the Thomsen‐Friedenreich (TF) antigen in cell membrane proteins occurs in 90% of adenocarcinomas. Additionally, the binding of the TF‐antigen to human galectin‐3 (Gal‐3), also frequently overexpressed in malignancy, promotes cancer progression and metastasis. In this context, structures that interfere with this specific interaction display the potential to prevent cancer metastasis. Herein, a multidisciplinary approach, combining the optimized synthesis of a TF‐antigen mimetic with NMR, X‐ray crystallography methods and isothermal titration calorimetry assays has been employed to unravel the molecular structural details that govern the Gal‐3/TF‐mimetic interaction. The TF‐mimetic presents a binding affinity for Gal‐3 similar to the TF‐natural antigen and retains the binding epitope and the bioactive conformation observed for the native antigen. Furthermore, from a thermodynamic perspective a decrease in the enthalpic contribution was observed for the Gal‐3/TF‐mimetic complex, however this behaviour is compensated by a favourable entropy gain. From a structural perspective, these results establish our TF‐mimetic as a scaffold to design multivalent solutions to potentially interfere with Gal‐3 aberrant interactions and likely be used to hamper Gal‐3‐mediated cancer cells adhesion and metastasis.
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Aug 2018
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