Spin-labeled Stearic Acid Behavior and Perturbations on the Structure of a Gel-Phase-Lipid Bilayer in Water: 5-, 12- and 16-SASL
- 4 December 2008
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry B
- Vol. 112 (51), 16830-16842
- https://doi.org/10.1021/jp806476a
Abstract
We have studied the effect of the insertion of spin-labeled molecules n-doxyl-stearic acid (n-SASL, n = 5, 12, 16) on the structure and dynamics of a model lipid bilayer in gel-like phases using molecular dynamics simulations. We have studied the atomic density depth profiles and configurations of the labeled molecules in a host hydrated stearic acid bilayer system. We have found that the 5-SASL label positions its paramagnetic group at the water-lipid interface, and its polar head builds H bonds to neighboring lipids and to the solvent. 16-SASL positions its paramagnetic group at the lipid-lipid interface. The 12-SASL label presents two configurations at high lateral pressure. In one configuration, the doxyl ring lays at the lipid-lipid interface, shifting its polar head toward the bilayer center. The other equilibrium configuration of 12-SASL presents its paramagnetic group laying in the center of the compact hydrophobic region of the layer (erected configuration). It was determined that the coexistence of these two configurations is governed by the polar head-water interaction. We have found that the insertion of the labeled molecules at the concentrations used in the present work (0.36 mol %) do not perturb global properties like area per lipid, tilt angle, or order parameters. Nevertheless, there are local perturbations of the host system that are confined to a 10 angstrom neighboring shell around the spin label molecule. To study the interactions that determine the position of the labeled molecules in the bilayer, we per-formed simulations at different lateral pressures, which allowed us to extract important conclusions.This publication has 38 references indexed in Scilit:
- Stearic Acid Spin Labels in Lipid Bilayers: Insight through Atomistic SimulationsThe Journal of Physical Chemistry B, 2007
- Detergent solubilization of bovine erythrocytes. Comparison between the insoluble material and the intact membraneBiophysical Chemistry, 2006
- Effects of a Short-Chain Ceramide on Bilayer Domain Formation, Thickness, and Chain Mobililty: DMPC and Asymmetric Ceramide MixturesBiophysical Journal, 2006
- Detergent resistant domains in erythrocyte membranes survive after cell cholesterol depletion: an EPR spin label studyChemistry and Physics of Lipids, 2003
- Differential effects of cholesterol on acyl chain order in erythrocyte membranes as a function of depth from the surface. An electron paramagnetic resonance (EPR) spin label studyBiophysical Chemistry, 2002
- A direct simulation of EPR slow-motion spectra of spin labelled phospholipids in liquid crystalline bilayers based on a molecular dynamics simulation of the lipid dynamicsPhysical Chemistry Chemical Physics, 2001
- Investigation of the Molecular Motion of Self-Assembled Fatty Acid FilmsThe Journal of Physical Chemistry B, 1998
- Depth dependence of the perturbing effect of placing a bulky group (oxazolidine ring spin labels) in the membrane on the membrane phase transitionBiochimica et Biophysica Acta (BBA) - Biomembranes, 1996
- The conformations of nitroxide-labelled fatty acid probes of membrane structure as studied by 2H-NMRBiochimica et Biophysica Acta (BBA) - Biomembranes, 1983
- Kernresonanzen in kristallinen Flüssigkeiten und in kristallinflüssigen Lösungen. Teil IZeitschrift für Naturforschung A, 1964