Title of Poster / Presentation
Differential Effects of Membrane Order on Membrane Permeability
Presentation Type
Poster
Start Date
5-8-2013 11:00 AM
Subjects
Membranes (Biology) -- Permeability, Cell membranes, Phospholipids
Abstract
Phospholipid membranes segregate into lateral domains of liquid ordered (lo) and liquid disordered (ld) phases when cholesterol and mixed species of lipids with saturated and unsaturated acyl chains are present. To examine membrane permeability and rate of vesicle rupture by Triton in pure lo, pure ld, and mixed lo/ld phases, LUVs were prepared based on the ternary phase diagram of POPC, sphingomyelin, and cholesterol. These LUVs were loaded with 2mM carboxyfluorescein (CF) and formed by extrusion at 65oC. Using a stopped-flow fluorometer, changes in CF fluorescence were measured when LUVs were exposed to sudden osmotic gradients, pH gradients, or 0.1% Triton. Acyl chain and phospholipid headgroup packing were assessed in all compositions with time-resolved measurements of DPH fluorescence lifetime and anisotropy decay. Water permeability was highest in the pure ld phase, and a factor of more than 100 lower in the pure lo phase. Proton permeability was lowest in the pure ld phase, and approximately five fold higher in the lo phase. The rate of membrane rupture was higher in the pure ld phase than in the pure lo phase, with inconsistent results in the coexistence region. Water permeability was found to correlate with acyl chain packing, decreasing with increased membrane order. Proton permeability increased exponentially with increasing membrane order.
Rights
© Copyright the author(s)
IN COPYRIGHT:
http://rightsstatements.org/vocab/InC/1.0/
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
DISCLAIMER:
The purpose of this statement is to help the public understand how this Item may be used. When there is a (non-standard) License or contract that governs re-use of the associated Item, this statement only summarizes the effects of some of its terms. It is not a License, and should not be used to license your Work. To license your own Work, use a License offered at https://creativecommons.org/
Persistent Identifier
http://archives.pdx.edu/ds/psu/9432
Included in
Differential Effects of Membrane Order on Membrane Permeability
Phospholipid membranes segregate into lateral domains of liquid ordered (lo) and liquid disordered (ld) phases when cholesterol and mixed species of lipids with saturated and unsaturated acyl chains are present. To examine membrane permeability and rate of vesicle rupture by Triton in pure lo, pure ld, and mixed lo/ld phases, LUVs were prepared based on the ternary phase diagram of POPC, sphingomyelin, and cholesterol. These LUVs were loaded with 2mM carboxyfluorescein (CF) and formed by extrusion at 65oC. Using a stopped-flow fluorometer, changes in CF fluorescence were measured when LUVs were exposed to sudden osmotic gradients, pH gradients, or 0.1% Triton. Acyl chain and phospholipid headgroup packing were assessed in all compositions with time-resolved measurements of DPH fluorescence lifetime and anisotropy decay. Water permeability was highest in the pure ld phase, and a factor of more than 100 lower in the pure lo phase. Proton permeability was lowest in the pure ld phase, and approximately five fold higher in the lo phase. The rate of membrane rupture was higher in the pure ld phase than in the pure lo phase, with inconsistent results in the coexistence region. Water permeability was found to correlate with acyl chain packing, decreasing with increased membrane order. Proton permeability increased exponentially with increasing membrane order.