Molecular organization in mixed SOPC and SDPC model membranes: Water permeability studies of polyunsaturated lipid
Shea Foley1, Elizabeth Miller1, Samuel Braziel1
1Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, NY 10801, USA.
Abstract:
Polyunsaturated phospholipids in plasma membranes modulate order and dynamics of the lipid bilayer and influence integral membrane protein function. In this study, we investigate the effects of polyunsaturated fatty acid (PUFA) chains in phosphatidylcholine (PC) on osmotic water permeability and packing characteristics, using a droplet interface bilayer (DIB) as a model cell membrane. The lipid bilayer system is composed of mixtures of PC lipids with varying ratio of 1-stearoyl-2-oleoylphosphatidylcholine (SOPC, 18: 0-18:1 PC) to 1-stearoyl-2-docosahexaenoylphosphatidylcholine (SDPC, 18:0-22:6 PC). Water permeability coefficients (Pf) were derived from the kinetics of osmotic filtration across the DIB. Confocal Raman microspectroscopy probed the structural and packing properties of the mixtures. The water transport parameters and Raman spectral analyses together indicate that Pf and aggregate ordering of a lipid bilayer are significantly influenced by the progressive addition of PUFA chains to a bilayer. The permeability rates across bilayers of the mixtures are a linear function of SDPC mol%. The mean disorder for the bilayer hydrocarbon region, as determined by Raman disorder parameter from the saturated chain, scales linearly with Pf. The linear trend for Pf versus degree of unsaturation in double-chain PC lipid bilayers is about half the value of that obtained for a single-chain lipid system, with implications for an evolutionary preference for phospholipids during the postulated biotic transition from single-chain lipid protocellular to modern cell membranes. The amassed results highlight the role of PUFA in modifying membrane order as manifest in bulk membrane physical properties, with characteristic differences depending on single-chain or double-chain systems.
More Related Videos
Related Concept Videos
Fluid Mosaic Model
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...
Membrane Fluidity
Asymmetric Lipid Bilayer
The Fluid Mosaic Model
Entropy and Solvation


