scholarly journals Studies of transmembrane peptides by pulse dipolar spectroscopy with semi-rigid TOPP spin labels

2021 ◽  
Author(s):  
Igor Tkach ◽  
Ulf Diederichsen ◽  
Marina Bennati
Keyword(s):  
Molecular Level ◽  
Dipolar Interaction ◽  
Spin Labels ◽  
Paramagnetic Centers ◽  
Structural Adaptation ◽  
Paramagnetic Resonance ◽  
Transmembrane Peptides ◽  
Distance Distributions ◽  
Lipid Environment ◽  
Electron Paramagnetic

AbstractElectron paramagnetic resonance (EPR)-based pulsed dipolar spectroscopy measures the dipolar interaction between paramagnetic centers that are separated by distances in the range of about 1.5–10 nm. Its application to transmembrane (TM) peptides in combination with modern spin labelling techniques provides a valuable tool to study peptide-to-lipid interactions at a molecular level, which permits access to key parameters characterizing the structural adaptation of model peptides incorporated in natural membranes. In this mini-review, we summarize our approach for distance and orientation measurements in lipid environment using novel semi-rigid TOPP [4-(3,3,5,5-tetramethyl-2,6-dioxo-4-oxylpiperazin-1-yl)-L-phenylglycine] labels specifically designed for incorporation in TM peptides. TOPP labels can report single peak distance distributions with sub-angstrom resolution, thus offering new capabilities for a variety of TM peptide investigations, such as monitoring of various helix conformations or measuring of tilt angles in membranes. Graphical Abstract

Jellyfish-like few-layer graphene nanoflakes: high paramagnetic response alongside increased interlayer interaction

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alexander Ulyanov ◽  
Dmitrii Stolbov ◽  
Serguei Savilov
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Sensitivity ◽  
Paramagnetic Centers ◽  
Interlayer Interaction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Graphene Nanoflakes ◽  
Few Layer Graphene ◽  
Electron Paramagnetic ◽  
Hydrocarbon Pyrolysis

Abstract Jellyfish-like graphene nanoflakes (GNF), prepared by hydrocarbon pyrolysis, are studied with electron paramagnetic resonance (EPR) method. The results are supported by X-ray photoelectron spectroscopy (XPS) data. Oxidized (GNFox) and N-doped oxidized (N-GNFox) flakes exhibit an extremely high EPR response associated with a large interlayer interaction which is caused by the structure of nanoflakes and layer edges reached by oxygen. The GNFox and N-GNFox provide the localized and mobile paramagnetic centers which are silent in the pristine (GNF p ) and N-doped (N-GNF) samples. The change in the relative intensity of the line corresponding to delocalized electrons is parallel with the number of radicals in the quaternary N-group. The environment of localized and mobile electrons is different. The results can be important in GNF synthesis and for explanation of their features in applications, especially, in devices with high sensitivity to weak electromagnetic field.

Pulsed electron–electron double resonance: beyond nanometre distance measurements on biomacromolecules

2011 ◽  
Vol 434 (3) ◽  
pp. 353-363 ◽  
Author(s):  
Gunnar W. Reginsson ◽  
Olav Schiemann
Keyword(s):  
Protein Complexes ◽  
Double Resonance ◽  
Resonance Method ◽  
Spin Labels ◽  
Coupling Mechanism ◽  
Distance Measurements ◽  
Paramagnetic Resonance ◽  
Distance Distributions ◽  
Nitroxide Spin Labels ◽  
Amino Acid Radicals

PELDOR (or DEER; pulsed electron–electron double resonance) is an EPR (electron paramagnetic resonance) method that measures via the dipolar electron–electron coupling distances in the nanometre range, currently 1.5–8 nm, with high precision and reliability. Depending on the quality of the data, the error can be as small as 0.1 nm. Beyond mere mean distances, PELDOR yields distance distributions, which provide access to conformational distributions and dynamics. It can also be used to count the number of monomers in a complex and allows determination of the orientations of spin centres with respect to each other. If, in addition to the dipolar through-space coupling, a through-bond exchange coupling mechanism contributes to the overall coupling both mechanisms can be separated and quantified. Over the last 10 years PELDOR has emerged as a powerful new biophysical method without size restriction to the biomolecule to be studied, and has been applied to a large variety of nucleic acids as well as proteins and protein complexes in solution or within membranes. Small nitroxide spin labels, paramagnetic metal ions, amino acid radicals or intrinsic clusters and cofactor radicals have been used as spin centres.

scholarly journals 2′-Alkynyl spin-labelling is a minimally perturbing tool for DNA structural analysis

2020 ◽  
Vol 48 (6) ◽  
pp. 2830-2840 ◽  
Author(s):  
Jack S Hardwick ◽  
Marius M Haugland ◽  
Afaf H El-Sagheer ◽  
Denis Ptchelkine ◽  
Frank R Beierlein ◽  
...  
Keyword(s):  
Epr Spectroscopy ◽  
Spin Labels ◽  
Resonance Spectroscopy ◽  
Conformational Ensemble ◽  
Dna Duplexes ◽  
Paramagnetic Resonance ◽  
Dynamics Simulations ◽  
Electron Paramagnetic ◽  
Spin Labelling

Abstract The determination of distances between specific points in nucleic acids is essential to understanding their behaviour at the molecular level. The ability to measure distances of 2–10 nm is particularly important: deformations arising from protein binding commonly fall within this range, but the reliable measurement of such distances for a conformational ensemble remains a significant challenge. Using several techniques, we show that electron paramagnetic resonance (EPR) spectroscopy of oligonucleotides spin-labelled with triazole-appended nitroxides at the 2′ position offers a robust and minimally perturbing tool for obtaining such measurements. For two nitroxides, we present results from EPR spectroscopy, X-ray crystal structures of B-form spin-labelled DNA duplexes, molecular dynamics simulations and nuclear magnetic resonance spectroscopy. These four methods are mutually supportive, and pinpoint the locations of the spin labels on the duplexes. In doing so, this work establishes 2′-alkynyl nitroxide spin-labelling as a minimally perturbing method for probing DNA conformation.

Electron paramagnetic resonance study of paramagnetic centers in carbon-fumed silica adsorbent

2014 ◽  
Vol 115 (13) ◽  
pp. 133704 ◽  
Author(s):  
D. V. Savchenko ◽  
B. D. Shanina ◽  
E. N. Kalabukhova ◽  
A. A. Sitnikov ◽  
V. S. Lysenko ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Fumed Silica ◽  
Electron Paramagnetic Resonance Study ◽  
Paramagnetic Centers ◽  
Paramagnetic Resonance ◽  
Silica Adsorbent ◽  
Electron Paramagnetic

scholarly journals Triarylmethyl Radicals: An EPR Study of 13C Hyperfine Coupling Constants

2017 ◽  
Vol 231 (4) ◽  
Author(s):  
Andrey A. Kuzhelev ◽  
Victor M. Tormyshev ◽  
Olga Yu. Rogozhnikova ◽  
Dmitry V. Trukhin ◽  
Tatiana I. Troitskaya ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Epr Spectroscopy ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Spin Labels ◽  
Spin Probes ◽  
Paramagnetic Resonance ◽  
Hyperfine Coupling Constants ◽  
Electron Paramagnetic ◽  
Triarylmethyl Radicals

AbstractTriarylmethyl (TAM) radicals are widely used in electron paramagnetic resonance (EPR) spectroscopy as spin labels and in EPR imaging as spin probes for

Ionic strength-dependent alterations of membrane structure of red blood cells

1986 ◽  
Vol 6 (11) ◽  
pp. 1007-1015 ◽  
Author(s):  
Andreas Herrmann ◽  
Peter Müller
Keyword(s):  
Ionic Strength ◽  
Membrane Structure ◽  
Spin Labels ◽  
Head Group ◽  
Polar Head Group ◽  
Paramagnetic Resonance ◽  
Group A ◽  
Hydrophobic Tail ◽  
Low Ionic Strength ◽  
Electron Paramagnetic

Electron paramagnetic resonance (EPR) measurements using various fatty acid spin labels were performed on membranes of intact human erythrocytes at physiological, and at low ionic strength. In the case of spin probes bearing the nitroxide near the polar head group, a less restricted motion at low ionic strength was seen than with those labels with a nitroxide deeper within the hydrophobic tail of the membrane. Although these data clearly show an influence of ionic strength on membrane structure, and possibly a modified protein-lipid interaction, they cannot be simply discussed in terms of an altered membrane fluidity.

Paramagnetic Defects and Photoluminescence in Carbon Rich a-SiC:H Films: Role of Hydrogen and Excess of Carbon

2007 ◽  
Vol 994 ◽  
Author(s):  
A. V. Vasin ◽  
A.A. Konchits ◽  
S.P. Kolesnik ◽  
A.V. Rusavsky ◽  
V.S. Lysenko ◽  
...  
Keyword(s):  
Annealing Temperature ◽  
Vacuum Annealing ◽  
Paramagnetic Centers ◽  
Paramagnetic Resonance ◽  
Killing Effect ◽  
Thermally Activated ◽  
Structure Reconstruction ◽  
Microstructure Model ◽  
Electron Paramagnetic

AbstractThe effect of excess of carbon in a-Si1−xCx:H has been studied with regard to local structure reconstruction, evolution of paramagnetic defects and photoluminescence (PL) after vacuum annealing over the temperature range 300–850°C. Two series of samples with stoichiometric (Si0.5C0.5) and carbon-rich (Si0.3C0.7) compositions were studied by Electron Paramagnetic Resonance (EPR), Photoluminescence (PL) and Raman scattering. It is found that there exist two effects responsible for the PL efficiency of a-Si1-xCx:H films: “killing” effect of carbon-related paramagnetic defects and “enhancing” effect of carbon-hydrogen bonds in Si:C-Hn configuration. A microstructure model is proposed for explaining the non-monotonic behavior of integrated PL intensity and concentration of paramagnetic centers and Si:C-Hn bonds as a function of annealing temperature. This model evolves from the following principal processes during thermal treatment of a-Si1−xCx:H: thermally activated release of weakly bonded hydrogen, migration of hydrogen within material and interaction of hydrogen with carbon-related defects.

Sign in / Sign up

Export Citation Format

Share Document