Related Experiment Video
Updated: Aug 11, 2026

Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy
Published on: October 24, 2017
An EPR study of the interfacial properties of phosphatidylcholine vesicles with different lipid chain lengths
Marilene Alves1, Miroslav Peric
1Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, CA 91330-8268, USA.
Abstract:
The hydrophobic spin probe 2,2,6,6-tetramethyl-piperidin-1-oxyl-4-yl octadecanoate (TEMPO-stearate) is used to study the interfacial properties of a variety of phosphatidylcholine vesicles. Since the spin probe exhibits a fast motional electron paramagnetic resonance (EPR) spectrum above the phase transition, the EPR spectrum of the spin probe is analyzed by nonlinear least-squares spectral fitting. EPR spectral line fitting provides high precision spectral parameters, which can be used to construct a detailed picture of the dynamics of the probe and its environment. The hyperfine coupling spacing is used to estimate the effective water concentration in the polar shell of vesicles, while the rotational correlation times give the information on the motion of the spin probe. The effective water concentration of the polar shell of dimyristoyl-phosphatidylglycerol (DMPG) vesicles is greater on average by about 4.0M than the effective water concentration of the polar shell of dimyristoyl-phosphatidylcholine (DMPC) vesicles. The effective water concentration decreases by about 0.5M for an increase of two carbons in the chain, and increases noticeably with hydrocarbon chain unsaturation, which is in good agreement with literature values. The nitroxide moiety rotates preferentially along the N-O bond, that is, parallel to its hydrocarbon chain.
Related Concept Videos
Synthesis of Phosphatidylcholine in the ER Membrane
The major components of all eukaryotic cell...
Asymmetric Lipid Bilayer
Assembly of the Lipid Bilayer in the ER
A large chunk of any biological membrane is composed of phospholipids. These lipids have a heterogeneous distribution across different subcellular organelles and even between...
Membrane Fluidity
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Membrane Fluidity
Phosphoinositides and PIPs
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...

