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Acyl chain disorder and azelaoyl orientation in lipid membranes containing oxidized lipids

Mendes Ferreira, Tiago; Sood, Rohit; Bärenwald, Ruth; Carlström, Göran LU ; Topgaard, Daniel LU ; Saalwächter, Kay; Kinnunen, Paavo K J and Ollila, O. H Samuli (2016) In Langmuir 32(25). p.6524-6533
Abstract

Oxidized phospholipids occur naturally in conditions of oxidative stress and have been suggested to play an important role in a number of pathological conditions due to their effects on a lipid membrane acyl chain orientation, ordering, and permeability. Here we investigate the effect of the oxidized phospholipid 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC) on a model membrane of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) using a combination of 13C-1H dipolar-recoupling nuclear magnetic resonance (NMR) experiments and united-atom molecular dynamics (MD) simulations. The obtained experimental order parameter SCH profiles show that the presence of 30 mol % PazePC in the bilayer... (More)

Oxidized phospholipids occur naturally in conditions of oxidative stress and have been suggested to play an important role in a number of pathological conditions due to their effects on a lipid membrane acyl chain orientation, ordering, and permeability. Here we investigate the effect of the oxidized phospholipid 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC) on a model membrane of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) using a combination of 13C-1H dipolar-recoupling nuclear magnetic resonance (NMR) experiments and united-atom molecular dynamics (MD) simulations. The obtained experimental order parameter SCH profiles show that the presence of 30 mol % PazePC in the bilayer significantly increases the gauche content of the POPC acyl chains, therefore decreasing the thickness of the bilayer, although with no stable bilayer pore formation. The MD simulations reproduce the disordering effect and indicate that the orientation of the azelaoyl chain is highly dependent on its protonation state with acyl chain reversal for fully deprotonated states and a parallel orientation along the interfacial plane for fully protonated states, deprotonated and protonated azelaoyl chains having negative and positive SCH profiles, respectively. Only fully or nearly fully protonated azelaoyl chain are observed in the 13C-1H dipolar-recoupling NMR experiments. The experiments show positive SCH values for the azelaoyl segments confirming for the first time that oxidized chains with polar termini adopt a parallel orientation to the bilayer plane as predicted in MD simulations.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
32
issue
25
pages
10 pages
publisher
The American Chemical Society
external identifiers
  • scopus:84976571785
  • wos:000378973300033
ISSN
0743-7463
DOI
10.1021/acs.langmuir.6b00788
language
English
LU publication?
yes
id
a4e674d6-ef14-401a-997c-178e30d8baa2
date added to LUP
2017-01-19 13:30:25
date last changed
2017-11-19 04:36:51
@article{a4e674d6-ef14-401a-997c-178e30d8baa2,
  abstract     = {<p>Oxidized phospholipids occur naturally in conditions of oxidative stress and have been suggested to play an important role in a number of pathological conditions due to their effects on a lipid membrane acyl chain orientation, ordering, and permeability. Here we investigate the effect of the oxidized phospholipid 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC) on a model membrane of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) using a combination of <sup>13</sup>C-<sup>1</sup>H dipolar-recoupling nuclear magnetic resonance (NMR) experiments and united-atom molecular dynamics (MD) simulations. The obtained experimental order parameter S<sub>CH</sub> profiles show that the presence of 30 mol % PazePC in the bilayer significantly increases the gauche content of the POPC acyl chains, therefore decreasing the thickness of the bilayer, although with no stable bilayer pore formation. The MD simulations reproduce the disordering effect and indicate that the orientation of the azelaoyl chain is highly dependent on its protonation state with acyl chain reversal for fully deprotonated states and a parallel orientation along the interfacial plane for fully protonated states, deprotonated and protonated azelaoyl chains having negative and positive S<sub>CH</sub> profiles, respectively. Only fully or nearly fully protonated azelaoyl chain are observed in the <sup>13</sup>C-<sup>1</sup>H dipolar-recoupling NMR experiments. The experiments show positive S<sub>CH</sub> values for the azelaoyl segments confirming for the first time that oxidized chains with polar termini adopt a parallel orientation to the bilayer plane as predicted in MD simulations.</p>},
  author       = {Mendes Ferreira, Tiago and Sood, Rohit and Bärenwald, Ruth and Carlström, Göran and Topgaard, Daniel and Saalwächter, Kay and Kinnunen, Paavo K J and Ollila, O. H Samuli},
  issn         = {0743-7463},
  language     = {eng},
  month        = {06},
  number       = {25},
  pages        = {6524--6533},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Acyl chain disorder and azelaoyl orientation in lipid membranes containing oxidized lipids},
  url          = {http://dx.doi.org/10.1021/acs.langmuir.6b00788},
  volume       = {32},
  year         = {2016},
}