Membrane water-penetration profiles from spin labels

  title={Membrane water-penetration profiles from spin labels},
  author={D. Marsh},
  journal={European Biophysics Journal},
  • D. Marsh
  • Published 2002
  • Chemistry, Medicine
  • European Biophysics Journal
Abstract. Spin label hyperfine splittings in mixtures of protic and aprotic solvents are used to obtain association constants KA,h for hydrogen bonding to oxazolidine nitroxides. With the Onsager approach to account for the variation in local dielectric constant, these results are used to determine the effective penetration profile of water into fluid phospholipid membranes, from recent electron paramagnetic resonance (EPR) studies on phospholipids spin-labelled systematically down the sn-2… Expand
Spin-Label EPR for Determining Polarity and Proticity in Biomolecular Assemblies: Transmembrane Profiles
  • D. Marsh
  • Chemistry, Medicine
  • Applied magnetic resonance
  • 2010
Applications to studies of the transverse polarity profiles in lipid bilayers, which constitute the permeability barrier of biological membranes, are reviewed and emphasis is given to parallels with the permeation profiles of oxygen and nitric oxide that are determined by using nonlinear continuous-wave EPR and saturation recovery EPR. Expand
Oxygen permeation profile in lipid membranes: comparison with transmembrane polarity profile.
Oxygen concentrates in the hydrophobic interior of phospholipid bilayer membranes with a sigmoidal permeation profile that is the inverse of the polarity profile established earlier for these spin-labeled lipids. Expand
Time-resolved electron spin resonance studies of spin-labelled lipids in membranes.
Two different applications of electron spin echo spectroscopy of spin-labelled phospholipids are reviewed, including the use of partially relaxed echo-detected ESR spectra to study the librational lipid-chain motions in the low-temperature phases of phospholIPid bilayers. Expand
Intramembrane polarity by electron spin echo spectroscopy of labeled lipids.
The association of water (D(2)O) with phospholipid membranes was studied by using pulsed-electron spin resonance techniques and results are in good agreement with more indirect measurements of the transmembrane polarity profile that are based on the (14)N-hyperfine splittings in the conventional continuous-wave electron spin resonance spectrum. Expand
Membrane curvature and cholesterol effects on lipids packing and spin-labelled lipids conformational distributions
Nitroxide spin-labelled lipid analogues are often used to study model membrane properties using EPR spectroscopy. Whereas in liquid phase membranes the spin label assumes, on average, its putativeExpand
Intramembrane water associated with TOAC spin-labeled alamethicin: electron spin-echo envelope modulation by D2O.
Electron spin-echo envelope modulation (ESEEM) spectroscopy was used to investigate the water exposure of TOAC-alamethicin introduced into membranes of saturated or unsaturated diacyl phosphatidylcholines that were dispersed in D2O, consistent with proposals of a critical concentration for switching between the two different membrane-associated states. Expand
Conformational distributions and hydrogen bonding in gel and frozen lipid bilayers: a high frequency spin-label ESR study.
The ESR parameters of PC spin labels in frozen membranes do not simply represent the membrane polarity or water penetration profile. Instead, they show a distribution between hydrogen-bonded (HB) andExpand
Polarity dependence of EPR parameters for TOAC and MTSSL spin labels: correlation with DOXYL spin labels for membrane studies.
The correlation between datasets for TOAC and DOXYL nitroxides in the various solvents is used to establish the polarity profile for isotropic hyperfine couplings of TOAC in a transmembrane peptide. Expand
Librational motion of spin-labeled lipids in high-cholesterol containing membranes from echo-detected EPR spectra.
Two-pulse, echo-detected electron paramagnetic resonance (EPR) spectroscopy was used to study the librational motions of spin-labeled lipids in membranes of dipalmitoylphosphatidylcholine + 50 mol % cholesterol, which are important for glass-like states and are generally relevant to high lipid packing densities, e.g., in cholesterol-containing raft domains and condensed complexes. Expand
Using spin polarised positive muons for studying guest molecule partitioning in soft matter structures.
The experimental technique which permits highly sensitive spectroscopy as previously demonstrated for surfactant mixtures is described and its capability in the study of partitioning of cosurfactant molecules in surfactants bilayers is demonstrated in order to elucidate the main factors which contribute to cosurFactant ordering at interfaces. Expand


Polarity contributions to hyperfine splittings of hydrogen-bonded nitroxides--the microenvironment of spin labels.
  • D. Marsh
  • Chemistry, Medicine
  • Journal of magnetic resonance
  • 2002
A self-consistent treatment of reaction field effects on isotropic (14)N hyperfine coupling constants of nitroxide spin labels in mixtures of polar and apolar solvents is given based on the OnsagerExpand
Medium effects on ESR spectra in studies of hydrogen-bonded transient solvent-solute complexes
The effect of solvent polarity on the observed hyperfine coupling constants of nitroxide radicals has been investigated both in the presence of and in the absence of hydrogen donors. With inertExpand
Hydrogen bond contribution to the isotropic hyperfine splitting constant of a nitroxide free radical
Abstract The increase in hyperfine splitting constant of nitroxide, due to hydrogen bond formation between the NO group of the radical and the solvent molecule is shown to be proportional to theExpand
Polarity and permeation profiles in lipid membranes
  • D. Marsh
  • Chemistry, Medicine
  • Proceedings of the National Academy of Sciences of the United States of America
  • 2001
The results are relevant not only to the permeation of water and polar solutes into membranes and their permeabilities, but also to depth determinations of site-specifically spin-labeled protein residues by using paramagnetic relaxation agents. Expand
Electric Moments of Molecules in Liquids