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Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers
Published on: July 22, 2015
Structure of fully hydrated fluid phase lipid bilayers with monounsaturated chains
Norbert Kucerka1, Stephanie Tristram-Nagle, John F Nagle
1Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, 15213, USA.
The Journal of Membrane Biology
|April 11, 2006
Summary
Quantitative structure analysis of hydrated lipid bilayers reveals that unsaturated fatty acid chains influence membrane thickness and area per lipid. Lipids with one or two unsaturated chains exhibit similar bilayer structures.
Area of Science:
- Biophysics
- Materials Science
- Structural Biology
Background:
- Phospholipids form the basis of cell membranes.
- The structure of lipid bilayers is influenced by fatty acid composition.
- Understanding lipid bilayer structure is crucial for cell function and drug delivery.
Purpose of the Study:
- To quantitatively determine the bilayer structures of palmitoyloleoylphosphatidylcholine (POPC) and dierucoylphosphatidylcholine (di22:1PC) at 30°C.
- To investigate the effect of fatty acid unsaturation on lipid bilayer properties.
- To compare the structural parameters of lipids with varying degrees of unsaturation.
Main Methods:
- X-ray scattering (low and high qz) from unilamellar vesicles and oriented bilayers.
- Volumetric measurements to determine form factors at zero scattering vector (F(0)).
- Hybrid electron density models to derive structural parameters from form factors.
Main Results:
- Determined area per lipid (A) for di22:1PC (69.3 ± 0.5 Ų) and POPC (68.3 ± 1.5 Ų), consistent with previous findings for dioleoylphosphatidylcholine (DOPC).
- Obtained quantitative values for five average bilayer thicknesses (hydrophobic, steric, head-head, phosphate-phosphate, and Luzzati).
- Compared structural data for POPC, di22:1PC, DOPC, and dimyristoylphosphatidylcholine (DMPC).
Conclusions:
- Lipids with monounsaturated chains exhibit bilayer structures closer to those with two unsaturated chains than to fully saturated lipids.
- Unsaturation in fatty acid chains significantly impacts quantitative bilayer structure.
- The study provides a quantitative basis for understanding the role of lipid unsaturation in membrane organization.
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