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

136 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
B23-Circular Dichroism I02-Macromolecular Crystallography	Crystal structure and metal binding properties of the periplasmic iron component EfeM from Pseudomonas syringae EfeUOB/M iron-transport system Mohan B. Rajasekaran , Rohanah Hussain , Giuliano Siligardi , Simon C. Andrews , Kimberly A. Watson Biometals 66 DOI: 10.1007/s10534-022-00389-2 Open Access Show Abstract ▼ Abstract: EfeUOB/M has been characterised in Pseudomonas syringae pathovar. syringae as a novel type of ferrous-iron transporter, consisting of an inner-membrane protein (EfeUPsy) and three periplasmic proteins (EfeOPsy, EfeMPsy and EfeBPsy). The role of an iron permease and peroxidase function has been identified for the EfeU and EfeB proteins, respectively, but the role of EfeO/M remains unclear. EfeMPsy is an ‘M75-only’ EfeO-like protein with a C-terminal peptidase-M75 domain (EfeOII/EfeM family). Herein, we report the 1.6 Å resolution crystal structure of EfeMPsy, the first structural report for an EfeM component of P. syringae pv. syringae. The structure possesses the bi-lobate architecture found in other bacterial periplasmic substrate/solute binding proteins. Metal binding studies, using SRCD and ICP-OES, reveal a preference of EfeMPsy for copper, iron and zinc. This work provides detailed knowledge of the structural scaffold, the metal site geometry, and the divalent metal binding potential of EfeM. This work provides crucial underpinning for a more detailed understanding of the role of EfeM/EfeO proteins and the peptidase-M75 domains in EfeUOB/M iron uptake systems in bacteria.	Mar 2022
B23-Circular Dichroism	Effect of trehalose and ceftriaxone on the stability of aggregating-prone tau peptide containing PHF6* sequence: an SRCD study Claudia Honisch , Federica Torni , Rohanah Hussain , Paolo Ruzza , Giuliano Siligardi International Journal Of Molecular Sciences 23 DOI: 10.3390/ijms23062932 Diamond Proposal Number(s): [23764, 25489] Open Access Show Abstract ▼ Abstract: The tau protein, a soluble protein associated with microtubules, which is involved in the assembly and stabilization of cytoskeletal elements, was found to form neurofibrillary tangles in different neurodegenerative diseases. Insoluble tau aggregates were observed to be organized in paired helical filaments (PHFs) and straight filaments (SFs). Recently, two small sequences (306–311 and 275–280) in the microtubule-binding region (MTBR), named PHF6 and PHF6, respectively, were found to be essential for tau aggregation. Since a possible therapeutic approach consists of impairing amyloid formation either by stabilizing the native proteins or reducing the level of amyloid precursors, here we use synchrotron radiation circular dichroism (SRCD) at Diamond B23 beamline to evaluate the inhibitory effects of two small molecules, trehalose and ceftriaxone, against the aggregation of a small peptide containing the PHF6 sequence. Our results indicate that both these molecules, ceftriaxone and trehalose, increased the stability of the peptide toward aggregation, in particular that induced by heparin. With trehalose being present in many fruits, vegetables, algae and processed foods, these results support the need to investigate whether a diet richer in trehalose might exert a protective effect toward pathologies linked to protein misfolding.	Mar 2022
B23-Circular Dichroism	Imaging deposition-dependent supramolecular chiral organisation C. Elizabeth Killalea , Mario Samperi , Giuliano Siligardi , David B. Amabilino Chemical Communications 9 DOI: 10.1039/D1CC06790G Diamond Proposal Number(s): [22017, 26044] Open Access Show Abstract ▼ Abstract: Thin films of a chiral diketopyrrolopyrrole derivative were imaged with spatially-defined Mueller Matrix Polarimetry, focussing on the Circular Dichroism signal, giving unique insight into the impact that deposition techniques and thermal annealing can have on chiral supramolecular structures in the solid state, where homogeneity was observed for spun-coated films while drop-coating afforded chiroptical diversity in the material, a feature invisible to absorption spectroscopy or optical microscopy.	Mar 2022
B23-Circular Dichroism	Spatially resolved chiroptical study of thin films of benzo[1,2‐ b :4,5‐ b’]dithiophene‐based oligothiophenes by synchrotron radiation electronic circular dichroism imaging (SR‐ECDi) technique Gianluigi Albano , Marcin Gorecki , Tamas Javorfi , Rohanah Hussain , Giuliano Siligardi , Gennaro Pescitelli , Lorenzo Di Bari Aggregate 10 DOI: 10.1002/agt2.193 Diamond Proposal Number(s): [17621] Open Access Show Abstract ▼ Abstract: The study of the chiroptical properties of thin-film samples of two chiral benzo[1,2-b:4,5-b’]dithiophene-based oligothiophenes with optoelectronic properties was carried out at Diamond B23 beamline using the synchrotron radiation electronic circular dichroism imaging (SR-ECDi) facility. The experimental results support the hypothesis that the non-reciprocal circularly polarized absorption observed in these materials is due to the combined linear dichroism and linear birefringence contributions. The mapping at 50-µm spatial resolution revealed that several species coexist in the mesoscopic chiral domains likely due to different aggregated phases, which were identified in the films by SR-ECDi but could not be detected with benchtop ECD instruments	Mar 2022
B23-Circular Dichroism	Self‐assembly of gold nanoparticles into an adjustable plasmonic 3D lattice using Janus‐type forked mesogenic ligands Yang-Yang Zhao , Yu Cao , Giuliano Siligardi , Georg H. Mehl , Feng Liu , Goran Ungar Chemistry – An Asian Journal DOI: 10.1002/asia.202200057 Diamond Proposal Number(s): [24437, 28686] Show Abstract ▼ Abstract: We report the formation of a 3D body-centred self-assembled superlattice of gold nanoparticles whose interparticle gap, and hence its plasmonic properties, are adjustable exclusively in the xy -plane. Thus, even though the particles are spherical, their anisotropic packing generates tailorable plasmonic dichroism. The gold nanoparticles are coated with forked ligands containing two mesogens: either two cholesterols (“twin”), one cholesterol and one azobenzene (“Janus”), or a mixture of the two. Beside the body-centered arrangement of gold nanoparticles, the structure also contains unusual two-dimensionally modulated smectic-like layers of mesogens in an egg-box geometry. Moreover, the presence of azobenzene mesogens allows the superlattice to be melted through UV-induced photo-isomerization; the process is reversible displaying low fatigue on repeated cycling.	Feb 2022
B23-Circular Dichroism	Electronic circular dichroism imaging (ECDi) casts a new light on the origin of solid-state chiroptical properties Marcin Gorecki , Filippo Lipparini , Gianluigi Albano , Tamas Javorfi , Rohanah Hussain , Giuliano Siligardi , Gennaro Pescitelli , Lorenzo Di Bari Chemistry – A European Journal 9 DOI: 10.1002/chem.202103632 Diamond Proposal Number(s): [17621, 19225] Show Abstract ▼ Abstract: Solid-state ECD (ss-ECD) spectra of a model microcrystalline solid, finasteride, dispersed into a KCl pellet were recorded by using the synchrotron radiation source at the Diamond B23 beamline. Scanning a surface of 36 mm2 with a step of 0.5 mm, we measured a set of ECD imaging (ECDi) spectra very different from each other and from the ss-ECD recorded with a bench-top instrument (1 cm2 area). This is due to the anisotropic part of the ECD (ACD), which averages to zero in solution or on a large number of randomly oriented crystallites, but can otherwise be extremely large. Two-way singular value decomposition (SVD) analysis, through experimental and simulated TDDFT spectra, disclosed that the measured and theoretical principal components are in line with each other. This finding demonstrates that the observed isotropic ss-ECD spectrum is governed by the anisotropy of locally oriented crystals. It also introduces a new quality for ss-ECD measurements and opens a new future for probing and mapping chiral materials in the solid state such as active pharmaceutical ingredients (APIs).	Dec 2021
B23-Circular Dichroism	Free radical generation in FAR-UV synchrotron radiation circular dichroism assays - protein and buffer composition contribution Paolo Ruzza , Claudia Honisch , Rohanah Hussain , Giuliano Siligardi International Journal Of Molecular Sciences 22 DOI: 10.3390/ijms222111325 Diamond Proposal Number(s): [17413] Open Access Show Abstract ▼ Abstract: A useful tool to analyze the ligands and/or environmental contribution to protein stability is represented by the Synchrotron Radiation Circular Dichroism UV-denaturation assay that consists in the acquisition of several consecutive repeated far-UV SRCD spectra. Recently we demonstrated that the prevailing mechanism of this denaturation involves the generation of free radicals and reactive oxygen species (ROS). In this work, we analyzed the effect of buffering agents commonly used in spectroscopic measurements, including MOPS (3-(N-morpholino) propanesulfonic acid), HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), TRIS-HCl (tris-hydroxymethil aminomethane hydrochloride), and phosphate, on the efficiency of protein denaturation caused by exposure to UV radiation. Fluorescence experiments confirmed the presence of ROS and were used to determine the rate of ROS generation. Our results indicate that the efficiency of the denaturation process is strongly influenced by the buffer composition with MOPS and HEPES acting also as scavengers and that the presence of proteins itself influenced the ROS formation rate.	Oct 2021
B23-Circular Dichroism	Asthma medication offers a potential new treatment for dementia Giuliano Siligardi Diamond Proposal Number(s): [17645, 24138] Show Abstract ▼ Abstract: Alzheimer’sdiseaseisaneurologicalconditionthataffectsthelargeageingpopulation.Thereiscurrentlynocureforthedisease,whichis associated with the formation of large protein plaques in the brain that kill neurons. A group of scientists led by Professor Middleton of Lancaster University, with the help of Diamond Light Source's Circular Dichroism beamline (B23) team, observed that the asthma drug salbutamol disrupted the formation of tau protein deposits that would otherwise accumulate in the brain. Salbutamol could, therefore, be a potential treatment for Alzheimer’s disease. The team conducted the laboratory study using various techniques. These revealed that salbutamol, by interacting with the tau protein, substantially prevented the formation of abnormal tangled clumps that at the early stages are thought to damage brain neurons and progressively induce dementia. In this work, high-throughput screening of libraries of generic chemicals enabled the identification of adrenalin as a successful candidate that precluded the formation of tau deposits. Subsequent screening of several drugs with similar chemical features identified salbutamol. Developing new drugs is slow and very expensive. It is far quicker and cheaper to repurpose clinically approved drugs for other diseases. This more economical approach can be applied to other neurological disorders (such as Parkinson’s and Huntington’s diseases) and any other disorder associated with protein deposits, such as type II diabetes, TTR amyloidosis and cancer.	Jul 2021
B23-Circular Dichroism	Interaction of a short peptide with G-quadruplex-forming sequences: An SRCD and CD study Claudia Honisch , Eugenio Ragazzi , Rohanah Hussain , John Brazier , Giuliano Siligardi , Paolo Ruzza Pharmaceutics 13 DOI: 10.3390/pharmaceutics13081104 Diamond Proposal Number(s): [21245] Open Access Show Abstract ▼ Abstract: G-quadruplex (G4) forming DNA sequences were recently found to play a crucial role in the regulation of genomic processes such as replication, transcription and translation, also related to serious diseases. Therefore, systems capable of controlling DNA and RNA G-quadruplex structures would be useful for the modulation of various cellular events. In particular, peptides represent good candidates for targeting G-quadruplex structures, since they are easily tailored to enhance their functionality. In this work, we analyzed, by circular dichroism and synchrotron radiation circular dichroism spectroscopies, the interaction of a 25-residue peptide deriving from RHAU helicases (Rhau25) with three G-quadruplex-forming oligonucleotide sequences, in both sodium- and potassium-containing buffers, the most relevant monovalent cations in physiological conditions. The peptide displayed greater affinity for the G4 sequences adopting a parallel structure. However, it showed the ability to also interact with antiparallel or hybrid G-quadruplex structures, inducing a conformation conversion to the parallel structure. The stability of the oligonucleotide structure alone or in presence of the Rhau25 peptide was studied by temperature melting and UV denaturation experiments, and the data showed that the interaction with the peptide stabilized the conformation of oligonucleotide sequences when subjected to stress conditions.	Jul 2021
B23-Circular Dichroism	Modelling the adsorption of proteins to nanoparticles at the solid-liquid interface Mikhail Soloviev , Giuliano Siligardi , Danilo Roccatano , Enrico Ferrari Journal Of Colloid And Interface Science 162 DOI: 10.1016/j.jcis.2021.07.072 Diamond Proposal Number(s): [27024] Show Abstract ▼ Abstract: Hypothesis: We developed a geometrical model to determine the theoretical maximum number of proteins that can pack as a monolayer surrounding a spherical nanoparticle. We applied our new model to study the adsorption of receptor binding domain (RBD) of the SARS-CoV-2 spike protein to silica nanoparticles. Due to its abundance and extensive use in manufacturing, silica represents a reservoir where the virus can accumulate. It is therefore important to study the adsorption and the persistence of viral components on inanimate surfaces. Experiments: We used previously published datasets of nanoparticle-adsorbed proteins to validate the new model. We then used integrated experimental methods and Molecular Dynamics (MD) simulations to characterise binding of the RBD to silica nanoparticles and the effect of such binding on RBD structure. Findings: The new model showed excellent fit with existing datasets and, combined to new RBD-silica nanoparticles binding data, revealed a surface occupancy of 32% with respect to the maximum RBD packing theoretically achievable. Up to 25% of RBD’s secondary structures undergo conformational changes as a consequence of adsorption onto silica nanoparticles. Our findings will help developing a better understanding of the principles governing interaction of proteins with surfaces and can contribute to control the spread of SARS-CoV-2 through contaminated objects.	Jul 2021

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