11,959 results match your criteria small-angle x-ray

Purification of Human Complement Component C4 and Sample Preparation for Structural Biology Applications.

Methods Mol Biol 2021 ;2227:249-264

Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.

Activated complement component C4 (C4b) is the nonenzymatic component of the classical pathway (CP) convertases of the complement system. Preparation of C4 and C4b samples suitable for structural biology studies is challenging due to low yields and complexity of recombinant C4 production protocols reported so far and heterogeneity of C4 in native sources. Here we present a purification protocol for human C4 and describe sample preparation methods for structural investigation of C4 and its complexes by crystallography, small angle X-ray scattering, and electron microscopy. Read More

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January 2021

Ubiquitin forms conventional decorated micelle structures with sodium dodecyl sulfate at saturation.

J Colloid Interface Sci 2021 Mar 24;596:233-244. Epub 2021 Mar 24.

Interdisciplinary Nanoscience Center (iNANO), Gustav Wieds Vej 14, Aarhus University, DK-8000 Aarhus, Denmark; Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, DK-8000 Aarhus, Denmark. Electronic address:

The anionic surfactant sodium dodecyl sulfate (SDS) interacts strongly with most globular proteins and denatures and unfolds them. While scattering studies using X-rays and neutrons have shown that this denaturation generally leads to protein-decorated SDS micelles, a different SDS-decorated polypeptide model has recently been suggested for complexes between SDS and Ubiquitin (UBI), in which individual SDS molecules are distributed on a partially stretched protein. To resolve this apparent discrepancy, we have investigated the SDS-UBI system by a number of complementary techniques. Read More

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Molecular basis of F-actin regulation and sarcomere assembly via myotilin.

PLoS Biol 2021 Apr 12;19(4):e3001148. Epub 2021 Apr 12.

Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria.

Sarcomeres, the basic contractile units of striated muscle cells, contain arrays of thin (actin) and thick (myosin) filaments that slide past each other during contraction. The Ig-like domain-containing protein myotilin provides structural integrity to Z-discs-the boundaries between adjacent sarcomeres. Myotilin binds to Z-disc components, including F-actin and α-actinin-2, but the molecular mechanism of binding and implications of these interactions on Z-disc integrity are still elusive. Read More

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Rigid monoclonal antibodies improve detection of SARS-CoV-2 nucleocapsid protein.

MAbs 2021 Jan-Dec;13(1):1905978

Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.

Monoclonal antibodies (mAbs) are the basis of treatments and diagnostics for pathogens and other biological phenomena. We conducted a structural characterization of mAbs against the N-terminal domain of nucleocapsid protein (NP) from SARS-CoV-2 using small-angle X-ray scattering and transmission electron microscopy. Our solution-based results distinguished the mAbs' flexibility and how this flexibility affects the assembly of multiple mAbs on an antigen. Read More

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High-pressure small-angle X-ray scattering cell for biological solutions and soft materials.

J Appl Crystallogr 2021 Feb 1;54(Pt 1):111-122. Epub 2021 Feb 1.

Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853, USA.

Pressure is a fundamental thermodynamic parameter controlling the behavior of biological macromolecules. Pressure affects protein denaturation, kinetic parameters of enzymes, ligand binding, membrane permeability, ion trans-duction, expression of genetic information, viral infectivity, protein association and aggregation, and chemical processes. In many cases pressure alters the molecular shape. Read More

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February 2021

Antimicrobial peptide induced colloidal transformations in bacteria-mimetic vesicles: Combining in silico tools and experimental methods.

J Colloid Interface Sci 2021 Mar 16;596:352-363. Epub 2021 Mar 16.

Department of Chemistry, University of Fribourg, Chemin Du Musée 9, 1700 Fribourg, Switzerland. Electronic address:

With the growing challenges of bacteria becoming resistant to conventional antibiotics, antimicrobial peptides (AMPs) may offer a potential alternative. One of the most studied AMPs, the human cathelicidin derived AMP LL-37 is notable for its antimicrobial activity even though its mechanism of action is not fully understood yet. This work investigates the interaction of LL-37 with 1-Palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-(1-glycerol) (POPG) vesicles, which were employed as a bacterial membrane model given the common presence of this phospholipid in the bacterial membrane. Read More

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Structural features of five types of maize starch granule subgroups sorted by flow cytometry.

Food Chem 2021 Mar 22;356:129657. Epub 2021 Mar 22.

Key Laboratory of Biology and Genetic Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling Shaanxi 712100, China. Electronic address:

Subgroups of starch granules from five maize phenotypes including waxy-, normal-, popcorn-, sweet corn- and high-amylose maize were sorted by flow cytometry (FC) utilizing the side scatter channel (SSC) and forward scatter channel (FSC). SSC and FSC mainly reflecting internal object complexity, and object size, respectively. Subgroups with higher FSC signal always showed higher SSC signal, indicating larger granules exhibited higher internal structural complexity. Read More

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Restoring structural parameters of lipid mixtures from small-angle X-ray scattering data.

J Appl Crystallogr 2021 Feb 1;54(Pt 1):169-179. Epub 2021 Feb 1.

Hamburg Outstation, European Molecular Biology Laboratory, Notkestrasse 85, Hamburg, 22607, Germany.

Small-angle X-ray scattering (SAXS) is widely utilized to study soluble macromolecules, including those embedded into lipid carriers and delivery systems such as surfactant micelles, phospho-lipid vesicles and bilayered nanodiscs. To adequately describe the scattering from such systems, one needs to account for both the form factor (overall structure) and long-range-order Bragg reflections emerging from the organization of bilayers, which is a non-trivial task. Presently existing methods separate the analysis of lipid mixtures into distinct procedures using form-factor fitting and the fitting of the Bragg peak regions. Read More

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February 2021

µDrop: a system for high-throughput small-angle X-ray scattering measurements of microlitre samples.

J Appl Crystallogr 2021 Feb 1;54(Pt 1):132-141. Epub 2021 Feb 1.

Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, 8010 Graz, Austria.

An automatic sample changer system for measurements of large numbers of liquid samples - the µDrop Sample Changer - is presented. It is based on a robotic arm equipped with a pipetting mechanism, which is combined with a novel drop-based sample holder. In this holder a drop of liquid is suspended between two parallel plates by surface tension. Read More

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February 2021

Estimation of the molecular weight of nanoparticles using a single small-angle X-ray scattering measurement on a relative scale.

Sci Rep 2021 Apr 8;11(1):7734. Epub 2021 Apr 8.

Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 06, Prague 6, Czech Republic.

Both small-angle scattering methods, X-rays (SAXS) and neutrons (SANS) rank among the methods that facilitate the determination of the molar mass of nanoparticles. Using this measure, aggregation or degradation processes are easy to follow. Mono- and multichain assemblies of nanoparticles in solution could be resolved, swelling ratio can also be obtained. Read More

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The Structure of the Potato Virus A Particles Elucidated by Small Angle X-Ray Scattering and Complementary Techniques.

Biochemistry (Mosc) 2021 Feb;86(2):230-240

Shubnikov Institute of Crystallography of Federal Scientific Research Centre "Crystallography and Photonics" of the Russian Academy of Sciences, Moscow, 119333, Russia.

Potato virus A (PVA) protein coat contains on its surface partially unstructured N-terminal domain of the viral coat protein (CP), whose structural and functional characteristics are important for understanding the mechanism of plant infection with this virus. In this work, we investigated the properties and the structure of intact PVA and partially trypsinized PVAΔ32 virions using small-angle X-ray scattering (SAXS) and complimentary methods. It was shown that after the removal of 32 N-terminal amino acids of the CP, the virion did not disintegrate and remained compact, but the helical pitch of the CP packing changed. Read More

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February 2021

Crystallization Induced Self-Assembly: A Strategy to Achieve Ultra-Small Domain Size.

Chemistry 2021 Apr 8. Epub 2021 Apr 8.

South China University of Technology, School of Molecular Science and Engineering, 318 Wushan Road, 510640, Guangzhou, CHINA.

Achieving self-assembled nanostructures with ultra-small feature sizes (e.g., below 5 nm) is an important prerequisite for the development of block copolymer lithography. Read More

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Selective removal of over-paintings from "Street Art" using an environmentally friendly nanostructured fluid loaded in highly retentive hydrogels.

J Colloid Interface Sci 2021 Mar 26;595:187-201. Epub 2021 Mar 26.

CSGI, Center for Colloids and Surface Science, University of Florence, via della Lastruccia, 3, 50019, Sesto Fiorentino, FI, Italy. Electronic address:

Hypothesis: The removal of over-paintings or graffiti is a priority for conservators and restorers. This operation is complex, especially when over-paintings lay on painted surfaces that must be preserved, as in the case of vandalism on street art, where the layers are usually chemically similar. Traditional methodologies often do not provide satisfactory results and pose health and eco-compatibility concerns. Read More

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Elicitation of potent serum neutralizing antibody responses in rabbits by immunization with an HIV-1 clade C trimeric Env derived from an Indian elite neutralizer.

PLoS Pathog 2021 Apr 7;17(4):e1008977. Epub 2021 Apr 7.

Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, India.

Evaluating the structure-function relationship of viral envelope (Env) evolution and the development of broadly cross-neutralizing antibodies (bnAbs) in natural infection can inform rational immunogen design. In the present study, we examined the magnitude and specificity of autologous neutralizing antibodies induced in rabbits by a novel HIV-1 clade C Env protein (1PGE-THIVC) vis-à-vis those developed in an elite neutralizer from whom the env sequence was obtained that was used to prepare the soluble Env protein. The novel 1PGE-THIVC Env trimer displayed a native like pre-fusion closed conformation in solution as determined by small angle X-ray scattering (SAXS) and negative stain electron microscopy (EM). Read More

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Nanostructure Transformation as a Signature of Oxygen Redox in Li-Rich 3d and 4d Cathodes.

J Am Chem Soc 2021 Apr 7. Epub 2021 Apr 7.

Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States.

Lithium-rich nickel manganese cobalt oxide (LRNMC) is being explored as an alternative to stoichiometric nickel manganese cobalt oxide (NMC) cathode materials due to its higher, initially accessible, energy-storage capacity. This higher capacity has been associated with reversible O oxidation; however, the mechanism through which the change in O chemistry is accommodated by the surrounding cathode structure remains incomplete, making it challenging to design strategies to mitigate poor electrode performance resulting from extended cycling. Focusing on LRNMC cathodes, we identify nanoscale domains of lower electron density within the cathode as a structural consequence of O oxidation using small-angle X-ray scattering (SAXS) and operando X-ray diffraction (XRD). Read More

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A Multi-Method Approach for Analyzing FapC Fibrillation and Determining Mass per Length.

Biophys J 2021 Apr 1. Epub 2021 Apr 1.

Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark; Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark. Electronic address:

Amyloid proteins are found in a wide range of organisms owing to the high stability of the β-sheet core of the amyloid fibrils. There are both pathological amyloids involved in various diseases and functional amyloids that play a beneficial role for the organism. The aggregation process is complex and often involves many different species. Read More

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The Histidine Phosphocarrier Kinase/Phosphorylase from Bacillus Subtilis Is an Oligomer in Solution with a High Thermal Stability.

Int J Mol Sci 2021 Mar 22;22(6). Epub 2021 Mar 22.

Dipartimento DiSVA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.

The histidine phosphocarrier protein (HPr) kinase/phosphorylase (HPrK/P) modulates the phosphorylation state of the HPr protein, and it is involved in the use of carbon sources by Gram-positive bacteria. Its X-ray structure, as concluded from crystals of proteins from several species, is a hexamer; however, there are no studies about its conformational stability, and how its structure is modified by the pH. We have embarked on the conformational characterization of HPrK/P of (bsHPrK/P) in solution by using several spectroscopic (namely, fluorescence and circular dichroism (CD)) and biophysical techniques (namely, small-angle X-ray-scattering (SAXS) and dynamic light-scattering (DLS)). Read More

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Effects of Silicon, Chromium, and Copper on Kinetic Parameters of Precipitation during Tempering of Medium Carbon Steels.

Materials (Basel) 2021 Mar 16;14(6). Epub 2021 Mar 16.

COMTES FHT a.s., Prumyslova 995, 334 41 Dobrany, Czech Republic.

Understanding the tempering behavior of medium carbon steels is mandatory if their mechanical properties are to be improved. For an optimal technology to be developed for this purpose, a substantial experimental basis is needed to extract quantitative information on the microstructure of the tempered material. This paper reports on the characterization of microstructural changes induced by tempering in medium-carbon steels alloyed with Si, Cr, Cu, and Mn using state-of-the-art experimental techniques. Read More

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Poly(Pyridinium Salt)s Containing 2,7-Diamino-9,9'-Dioctylfluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties.

Molecules 2021 Mar 12;26(6). Epub 2021 Mar 12.

Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (H), and fluorine 19 (F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Ms) between 96. Read More

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Electronics of Anion Hot Injection-Synthesized Te-Functionalized Kesterite Nanomaterial.

Nanomaterials (Basel) 2021 Mar 19;11(3). Epub 2021 Mar 19.

SensorLab (University of the Western Cape Sensor Laboratories), University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.

Metal chalcogenides such as copper zinc tin sulfide (CZTS) have been intensively studied as potential photovoltaic cell materials, but their viability have been marred by crystal defects and low open circuit potential () deficit, which affected their energy conversion efficiency. Strategies to improve on the properties of this material such as alloying with other elements have been explored and have yielded promising results. Here, we report the synthesis of CZTS and the partial substitution of S with Te via anion hot injection synthesis method to form a solid solution of a novel kesterite nanomaterial, namely, copper zinc tin sulfide telluride (CZTSTe). Read More

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Monovalent Salt and pH-Induced Gelation of Oxidised Cellulose Nanofibrils and Starch Networks: Combining Rheology and Small-Angle X-ray Scattering.

Polymers (Basel) 2021 Mar 19;13(6). Epub 2021 Mar 19.

Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.

Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised cellulose nanofibril (OCNF) and starch-based hydrogels. Addition of NaCl caused an increased stiffness of the OCNF:starch (1:1 wt%) blend gels, where salt played an important role in reducing the repulsive OCNF fibrillar interactions. Read More

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Modulation of Human Phenylalanine Hydroxylase by 3-Hydroxyquinolin-2(1H)-One Derivatives.

Biomolecules 2021 Mar 19;11(3). Epub 2021 Mar 19.

Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.

Phenylketonuria (PKU) is a genetic disease caused by deficient activity of human phenylalanine hydroxylase (hPAH) that, when untreated, can lead to severe psychomotor impairment. Protein misfolding is recognized as the main underlying pathogenic mechanism of PKU. Therefore, the use of stabilizers of protein structure and/or activity is an attractive therapeutic strategy for this condition. Read More

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Wide-Ranging Multitool Study of Structure and Porosity of PLGA Scaffolds for Tissue Engineering.

Polymers (Basel) 2021 Mar 25;13(7). Epub 2021 Mar 25.

Institute of Photon Technologies of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Pionerskaya 2, Troitsk, 108840 Moscow, Russia.

In this study, the nanoscale transformation of the polylactic-co-glycolic acid (PLGA) internal structure, before and after its supercritical carbon dioxide (sc-CO) swelling and plasticization, followed by foaming after a CO pressure drop, was studied by small-angle X-ray scattering (SAXS) for the first time. A comparative analysis of the internal structure data and porosity measurements for PLGA scaffolds, produced by sc-CO processing, on a scale ranging from 0.02 to 1000 μm, was performed by SAXS, helium pycnometry (HP), mercury intrusion porosimetry (MIP) and both "lab-source" and synchrotron X-ray microtomography (micro-CT). Read More

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The Micellization of Well-Defined Single Graft Copolymers in Block Copolymer/Homopolymer Blends.

Polymers (Basel) 2021 Mar 9;13(5). Epub 2021 Mar 9.

Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P.O. Box 1527, 71110 Heraklion Crete, Greece.

A series of well-defined (polyisoprene)(polystyrene), IS, single graft copolymers with similar total molecular weights but different compositions, , were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar characteristics were studied by small-angle x-ray scattering. To investigate the effect of macromolecular architecture on the formation and characteristics of micelles, the results on the single graft copolymers were compared with those of the corresponding linear polystyrene--polyisoprene diblock copolymers, SI. The comparison reveals that the polystyrene core chains are more stretched in the case of graft copolymer micelles. Read More

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Structural Analysis of Melt-Spun Polymer-Optical Poly(Methyl Methacrylate) Fibres by Small-Angle X-ray Scattering and Monte-Carlo Simulation.

Polymers (Basel) 2021 Mar 3;13(5). Epub 2021 Mar 3.

Hochschule für Technik, Wirtschaft und Kultur Leipzig (HTWK), Zschochersche Str. 69, 04229 Leipzig, Germany.

The structural properties, mainly the spatial variation of density and chain interaction, of melt-spun polymer optical fibres (POFs) are investigated by small-angle X-ray scattering (SAXS) and compared to Monte-Carlo polymer simulations. The amorphous PMMA POFs had been subjected to a rapid cooling in a water quench right after extrusion in order to obtain a radial refractive-index profile. Four fibre samples with different processing parameters are investigated and the SAXS data analysed via Guinier approach. Read More

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