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Updated: Jul 11, 2026

Realistic Membrane Modeling Using Complex Lipid Mixtures in Simulation Studies
Published on: September 1, 2023
Stearic acid spin labels in lipid bilayers: insight through atomistic simulations
Lorna Stimson1, Lei Dong, Mikko Karttunen
1Laboratory of Physics, Helsinki University of Technology, Finland.
Abstract:
Spin-labeled stearic acid species are commonly used for electron paramagnetic resonance (EPR) studies of cell membranes to investigate phase transitions, fluidity, and other physical properties. In this paper, we use large-scale molecular dynamics simulations to investigate the position and behavior of nitroxide spin labels attached to stearic acid molecules in dipalmitoylphosphatidylcholine (DPPC) bilayers. The results of these studies are potentially very important for the interpretation of EPR spectra, which rely on assumptions about the position of the label in the membrane. Additionally, we investigate the effect of chirality and ionization of the carboxyl group of the label. For a non-ionized species, we observe that spin-label molecules are even able to make flip-flop transitions between the leaflets of the bilayer. Such transitions have been previously observed only in very rare cases in molecular simulations.
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