Publications by authors named "Vsevolod A Livshits"
We study the molecular dynamics and structures of the guest-host complexes of cucurbituril, CB[7], with spin probes through the conventional electron spin resonance (ESR), saturation transfer ESR (STESR), density functional theory (DFT), and molecular dynamics (MD) computations. Protonated TEMPOamine (), a derivative of TEMPO having a positive charge and an octyl group on the quaternary nitrogen atom (), and the neutral spin-labeled indole () are used as guests. To eliminate the overall complex rotation, the solutions of complexes in a solid CB[7] matrix were prepared.
View Article and Find Full Text PDFFor canonical lipid raft mixtures of cholesterol (chol), N-palmitoylsphingomyelin (PSM), and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), electron paramagnetic resonance (EPR) of spin-labeled phospholipids--which is insensitive to domain size--is used to determine the ternary phase diagram at 23°C. No phase boundaries are found for binary POPC/chol mixtures, nor for ternary mixtures with PSM content <24 mol %. EPR lineshapes indicate that conversion from the liquid-disordered (L(α)) to liquid-ordered (L(o)) phase occurs continuously in this region.
View Article and Find Full Text PDFArticle Synopsis
- Transmembrane oxygen profiles in lipid bilayers are crucial for understanding membrane function and assist in determining the structure of membrane proteins using site-directed spin labeling.
- These oxygen profiles show a specific Boltzmann sigmoidal distribution depending on how deep you are into the lipid layers, indicating a two-part system between the outer and inner regions of the membrane.
- The research confirms that the oxygen profiles derived from spin-labeled lipids align with previously established profiles from a specific transmembrane peptide, allowing for the reconstruction of the entire bilayer structure from a single layer.
High-field EPR of spin-labelled lipid chains has proved to be an extremely productive means for biophysical investigations of phospholipid bilayer membranes. Results on the following three topics are reviewed: 1. Non-axial ordering of lipid chains in cholesterol-containing membranes; 2.
View Article and Find Full Text PDFArticle Synopsis
- The text discusses how oxygen permeation in membranes relates to physiological functions and techniques for determining membrane depths using site-directed spin labeling.
- Spin-lattice relaxation enhancements from oxygen were measured in phosphatidylcholines using electron paramagnetic resonance (EPR), revealing similar oxygen profiles through various EPR methods.
- Findings indicate that oxygen accumulates in the hydrophobic core of lipid membranes and that the oxygen permeation profile differs at protein interfaces compared to fluid lipid bilayers, influenced by water penetration and polarity.
High-field electron spin resonance (ESR) spectroscopy is currently undergoing rapid development. This considerably increases the versatility of spin labelling which, at conventional field strengths, is already well established as a powerful physical technique in membrane biology. Among the unique advantages offered by high-field spectroscopy, particularly for spin-labelled lipids, are sensitivity to non-axial rotation and lateral ordering, a better orientational selection, an extended application to rotational dynamics, and an enhanced sensitivity to environmental polarity.
View Article and Find Full Text PDF