B23-Circular Dichroism
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Maryam
Abooali
,
Xi
Lei
,
Inna M.
Yasinska
,
Stephanie
Schlichtner
,
Rohanah
Hussain
,
Giuliano
Siligardi
,
Tiberiu-Marius
Gianga
,
Steffen M.
Berger
,
Dietmar
Cholewa
,
Bernhard F.
Gibbs
,
Elizaveta
Fasler-Kan
,
Vadim V.
Sumbayev
Diamond Proposal Number(s):
[36941, 38189]
Open Access
Abstract: Background: VISTA is a unique multifunctional immune checkpoint protein, which can display both receptor and ligand properties. It plays a crucial role in the cancer immune evasion machinery operated by a wide range of human malignancies and may thus be considered as a potential target for immunotherapy of cancer. Receptors of VISTA through which this protein transmits immunosuppressive signals under various normal and pathological conditions remain to be identified. Materials and Methods: To conduct the study, we used human recombinant proteins and various human cell lines as well as primary T cells. A wide range of techniques including tissue culture and co-cultures, Western blot analysis, on-cell Western, ELISA, co-immunoprecipitation, biochemical assays and synchrotron radiation circular dichroism spectroscopy were employed. Results: Here we report for the first time that VISTA has affinity to PD-1 and binds it as a ligand. We found that when interacting with PD-1, VISTA suppresses IL-2 production by T helper cells. These effects were confirmed in the in vitro and ex vivo experiments. Affinity of VISTA to PD-1 was also characterised and found to be moderate, with a Kd of approximately 2.3 μM detected by synchrotron radiation circular dichroism spectroscopy. Conclusions: These results open a completely new chapter in our understanding of the concept of immune checkpoint proteins, where some of them clearly show both ligand and receptor activities and display multifunctional properties.
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Nov 2025
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[32878]
Abstract: Conventional electronic circular dichroism (ECD) spectroscopy fails when it comes to distinguishing chiral compounds with identical or nearly similar spectra. But what if we could harness solid-state anisotropy to break this limitation? In this article, it is demonstrated how CD anisotropy (CDA) uncovers critical differences between two well-known packing polymorphs of finasteride despite their nearly similar pellet ECD spectra. Using ECD imaging (ECDi) and TDDFT-simulated spectra from X-ray structures, it is shown that the second polymorphic form exhibits a unique CDA signature, setting it apart from the first polymorphic form. This proof-of-concept study paves the way for a new strategy to differentiate chiral solid-state systems that conventional methods might struggle to resolve.
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Aug 2025
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[34241, 37661]
Open Access
Abstract: The development of molecules that interact with G-quadruplex (G4) sequences requires effective evaluation methods. Several techniques are currently available, including nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and mass spectrometry (MS), fluorescence using FRET-melting, G4-fluorescent intercalator displacement assay (G4-FID) and affinity chromatography. Among these, CD spectroscopy is gaining prominence due to its lower material requirements, faster experimentation and quicker data processing. However, conventional CD methods have limitations, such as higher sample volume required and the inability to handle high-throughput analysis efficiently. The use of synchrotron radiation in high-throughput analysis methods (HT-SRCD) has further advanced the investigation of small-molecule interactions with DNA G4 structures in the presence of various monovalent cations. HT-SRCD offers the capability to analyze multiple samples simultaneously, overcoming the limitations of conventional CD methods. To validate this approach, three biologically relevant G4 sequences—HTelo1, G3T3 and T95-2T—were investigated. Their interactions with a library of small tetrazole-based molecules, synthesized via a four-component Ugi reaction, and with a peptide sequence deriving from RHAU helicases (Rhau25), were evaluated. The results demonstrate that this method not only effectively discriminates between different ligands but also provides valuable insights into the selectivity and the modes of interaction of these ligands with the G4 sequences.
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Aug 2025
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B23-Circular Dichroism
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Abstract: The interaction between lipids and proteins impacts on a multitude of cellular processes and may contribute to the onset of several pathologies and ageing. Such processes are frequently linked to oxidative stress, whereby polyunsaturated fatty acids act as substrates for in vivo lipoxidation. The subsequent lipid peroxidation and/or isomerisation is known to affect membrane organization, as well as to modify proteins and DNA, leading to functional alterations. Aim of this study was to evaluate the capacity of UV denaturation experiments to induce lipid modification and to investigate the influence of lipid presence on the conformational stability of selected soluble model proteins. To this end, the UV-denaturation experiment developed at the B23 beamline of the Diamond Light Source (UK) is employed, which high photon flux and brilliance of the incident beamlight induce protein denaturation when repeated consecutive synchrotron radiation circular dichroism spectra are acquired in the far-UV region, diagnostic of protein folding. This allows the estimation of protein photostability. Our findings show that the presence of lipid vesicles (SUVs) significantly impacts the UV-denaturation of proteins, preserving the native structure in proteins with a high helical content. This suggests that lipids may play a protective role against light-induced damage to proteins.
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May 2025
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B23-Circular Dichroism
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Maryam
Abooali
,
Stephanie
Schlichtner
,
Xi
Lei
,
Nijas
Aliu
,
Sabrina
Ruggiero
,
Sonia
Loges
,
Martin
Ziegler
,
Franziska
Hertel
,
Anna-Lena
Volckmar
,
Albrecht
Stenzinger
,
Petros
Christopoulos
,
Michael
Thomas
,
Elena
Klenova
,
N. Helge
Meyer
,
Stergios
Boussios
,
Nigel
Heaton
,
Yoh
Zen
,
Ane
Zamalloa
,
Shilpa
Chokshi
,
Luca
Urbani
,
Sophie
Richard
,
Kavitha
Kirubendran
,
Rohanah
Hussain
,
Giuliano
Siligardi
,
Dietmar
Cholewa
,
Steffen M.
Berger
,
Inna M.
Yasinska
,
Elizaveta
Fasler-Kan
,
Vadim V.
Sumbayev
Diamond Proposal Number(s):
[24509, 20755, 21202]
Open Access
Abstract: V-domain Ig-containing suppressor of T cell activation (VISTA) is a unique immune checkpoint protein, which was reported to display both receptor and ligand activities. However, the mechanisms of regulation of VISTA activity and functions by factors of tumour microenvironment (TME) remain unclear and understanding these processes is required in order to develop successful personalised cancer immunotherapeutic strategies and approaches. Here we report for the very first time that VISTA interacts with another immune checkpoint protein galectin-9 inside the cell most likely facilitating its interaction with TGF-β-activated kinase 1 (TAK1). This process is required for protection of lysosomes, which is crucial for many cell types and tissues. We found that VISTA expression can be differentially controlled by crucial factors present in TME, such as transforming growth factor beta type 1 (TGF-β) and hypoxia as well as other factors activating hypoxic signalling. We confirmed that involvement of these important pathways modulated by TME differentially influences VISTA expression in different cell types. These networks include: TGF-β-Smad3 pathway, TAK1 (TGF-β-activated kinase 1) or apoptosis signal-regulating kinase 1 (ASK1)-induced activation of activating transcription factor 2 (ATF-2) and hypoxic signalling pathway. Based on this work we determined the five critical functions of VISTA and the role of TME factors in controlling (modulating or downregulating) VISTA expression.
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Feb 2025
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B23-Circular Dichroism
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Gianluigi
Albano
,
Marco
Bertuolo
,
Francesco
Zinna
,
Andrea
Taddeucci
,
Tamas
Javorfi
,
Rohanah
Hussain
,
Gianluca M.
Farinola
,
Gennaro
Pescitelli
,
Angela
Punzi
,
Giuliano
Siligardi
,
Lorenzo
Di Bari
Diamond Proposal Number(s):
[36727]
Abstract: The development of chiral organic materials with strong non-reciprocal chiroptical features may have major implications for cutting-edge technological applications. In this work, a new ad hoc synthesized chiral 1,4-diketo-3,6-dithienylpyrrolo[3,4-c]pyrrole dye, bearing two (S)-3,7-dimethyl-1-octyl alkyl chains on the lactam moieties and functionalized with two lateral 9-anthracenyl π-conjugated units, exhibited strong non-reciprocal chiroptical properties in thin films, with some important differences between samples prepared by drop casting and spin coating. A detailed study was performed to unravel the intimate structure–property relationship, involving computational analysis, different microscopy techniques and synchrotron radiation Mueller matrix polarimetry imaging (SR-MMPi) investigation. Through SR-MMPi, exploiting the highly collimated synchrotron radiation (SR) light of Diamond Light Source B23 beamline, we determined the size of the linear contributions responsible for the strong non-reciprocal features, and how they manifest in the various 2D chiral meso-domains.
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Jan 2025
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[2083, 17666, 15028, 10537, 8674]
Open Access
Abstract: A new technology to write and read covert information in authentication labels is described. This technology uses the phenomenon of photo-induced chirality in Ge2Sb2Te5 thin films to encode the left- or right-circular or linear polarization of the laser beam used to write the label. The written polarization can be revealed by a simple reading device, which is demonstrated to provide the same qualitative information as reading based on cyclotron circular dichroism spectroscopy and imaging. The suggested method, while based on existing manufacturing approaches, offers a balance between technological complexity for writing and simplicity for reading, and may be advantageous as a new authentication technology.
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Oct 2024
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B23-Circular Dichroism
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Cédric
Couturier
,
Quentin
Ronzon
,
Giulia
Lattanzi
,
Iain
Lingard
,
Sebastien
Coyne
,
Veronique
Cazals
,
Nelly
Dubarry
,
Stephane
Yvon
,
Corinne
Leroi-Geissler
,
Obdulia Rabal
Gracia
,
Joanne
Teague
,
Sylvie
Sordello
,
David
Corbett
,
Caroline
Bauch
,
Chantal
Monlong
,
Lloyd
Payne
,
Thomas
Taillier
,
Hazel
Fuchs
,
Mark
Broenstrup
,
Peter H.
Harrison
,
Lucile
Moynie
,
Abirami
Lakshminarayanan
,
Tiberiu-Marius
Gianga
,
Rohanah
Hussain
,
James H.
Naismith
,
Michael
Mourez
,
Eric
Bacqué
,
Fredrik
Björkling
,
Jean-Francois
Sabuco
,
Henrik
Franzyk
Diamond Proposal Number(s):
[26447]
Abstract: Tridecaptins comprise a class of linear cationic lipopeptides with an N-terminal fatty acyl moiety. These 13-mer antimicrobial peptides consist of a combination of d- and l-amino acids, conferring increased proteolytic stability. Intriguingly, they are biosynthesized by non-ribosomal peptide synthetases in the same bacterial species that also produce the cyclic polymyxins displaying similar fatty acid tails. Previously, the des-acyl analog of TriA1 (termed H-TriA1) was found to possess very weak antibacterial activity, albeit it potentiated the effect of several antibiotics. In the present study, two series of des-acyl tridecaptins were explored with the aim of improving the direct antibacterial effect. At the same time, overall physico-chemical properties were modulated by amino acid substitution(s) to diminish the risk of undesired levels of hemolysis and to avoid an impairment of mammalian cell viability, since these properties are typically associated with highly hydrophobic cationic peptides. Microbiology and biophysics tools were used to determine bacterial uptake, while circular dichroism and isothermal calorimetry were used to probe the mode of action. Several analogs had improved antibacterial activity (as compared to that of H-TriA1) against Enterobacteriaceae. Optimization enabled identification of the lead compound 29 that showed a good ADMET profile as well as in vivo efficacy in a variety of mouse models of infection.
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Feb 2024
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B23-Circular Dichroism
I24-Microfocus Macromolecular Crystallography
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Ryan M.
Lithgo
,
Marko
Hanževački
,
Gemma
Harris
,
Jos J. A. G.
Kamps
,
Ellie
Holden
,
Tiberiu-Marius
Gianga
,
Justin L. P.
Benesch
,
Christof M.
Jäger
,
Anna K.
Croft
,
Rohanah
Hussain
,
Jon L.
Hobman
,
Allen M.
Orville
,
Andrew
Quigley
,
Stephen B.
Carr
,
David J.
Scott
Open Access
Abstract: The periplasmic chaperone SilF has been identified as part of an Ag(I) detoxification system in Gram negative bacteria. Sil proteins also bind Cu(I), but with reported weaker affinity, therefore leading to the designation of a specific detoxification system for Ag(I). Using isothermal titration calorimetry we show that binding of both ions is not only tighter than previously thought, but of very similar affinities. We investigated the structural origins of ion binding using molecular dynamics and QM/MM simulations underpinned by structural and biophysical experiments. The results of this analysis showed that the binding site adapts to accommodate either ion, with key interactions with the solvent in the case of Cu(I). The implications of this are that Gram negative bacteria do not appear to have evolved a specific Ag(I) efflux system but take advantage of the existing Cu(I) detoxification system. Therefore, there are consequences for how we define a particular metal resistance mechanism and understand its evolution in the environment.
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Oct 2023
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[10479, 9785]
Open Access
Abstract: Bleomycin is a glycopeptide congeners’ family of antitumor antibiotics employed for the treatment of several types of tumors such as squamous cell carcinomas and malignant lymphomas. The general chemical structure is constituted by three main portions: (i) a metal binding domain that is recognized to be responsible for the DNA cleavage activity; (ii) a DNA binding domain via the 1-4’ bithiazole moiety; and (iii) a carbohydrate domain thought to be responsible for the accumulation of bleomycin in some cancer cells. To date, a limited number of protein interactions with bleomycin have been studied, but the plasma binding has not yet been determined. Here, we explore this aspect of the protein binding capacity of bleomycin to the two most abundant plasma proteins, human serum albumin (HSA) and α1-acid glycoprotein (AGP), which are known to bind and to be carriers of many drug molecules using spectroscopic techniques, such as circular dichroism, UV-vis absorbance, and fluorescence. The results showed that bleomycin binds to plasma proteins with an order-of-magnitude higher affinity for AGP than HSA. This is particularly important as AGP is an acute phase protein and is overexpressed in cancer patients. This should be taken into consideration as it could affect the therapeutic effect of the bleomycin dosage.
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Aug 2023
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