Influence of the lipid backbone on electrochemical phase behavior

Philip N Jemmett, David C Milan, Richard J Nichols, Thomas Howitt, Alexandra Martin, Thomas Arnold, Jonathan L Rawle, Christopher L Nicklin, Timothy R Dafforn, Liam R Cox, Sarah L Horswell*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Sphingolipids are an important class of lipids found in mammalian cell membranes with important structural and signaling roles. They differ from another major group of lipids, the glycerophospholipids, in the connection of their hydrocarbon chains to their headgroups. In this study, a combination of electrochemical and structural methods has been used to elucidate the effect of this difference on sphingolipid behavior in an applied electric field. N-Palmitoyl sphingomyelin forms bilayers of similar coverage and thickness to its close analogue di-palmitoyl phosphatidylcholine. Grazing incidence diffraction data show slightly closer packing and a smaller chain tilt angle from the surface normal. Electrochemical IR results at low charge density show that the difference in tilt angle is retained on deposition to form bilayers. The bilayers respond differently to increasing electric field strength: chain tilt angles increase for both molecules, but sphingomyelin chains remain tilted as field strength is further increased. This behavior is correlated with disruption of the hydrogen-bonding network of small groups of sphingomyelin molecules, which may have significance for the behavior of molecules in lipid rafts in the presence of strong fields induced by ion gradients or asymmetric distribution of charged lipids.
Original languageEnglish
Pages (from-to)14290-14301
Number of pages12
JournalLangmuir
Volume38
Issue number46
Early online date10 Nov 2022
DOIs
Publication statusE-pub ahead of print - 10 Nov 2022

Keywords

  • sphingomyelin
  • adsorption
  • phospholipid
  • biomimetic membrane
  • spectroelectrochemistry
  • infrared spectroscopy
  • hydrogen bonding
  • Grazing Incidence X-ray Diffraction
  • Article

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