Interfacial tension and surface pressure of high density lipoprotein, low density lipoprotein, and related lipid droplets.

Research output: Contribution to journalArticle

Abstract

Lipid droplets play a central role in energy storage and metabolism on a cellular scale. Their core is comprised of hydrophobic lipids covered by a surface region consisting of amphiphilic lipids and proteins. For example, high and low density lipoproteins (HDL and LDL, respectively) are essentially lipid droplets surrounded by specific proteins, their main function being to transport cholesterol. Interfacial tension and surface pressure of these particles are of great interest because they are related to the shape and the stability of the droplets and to protein adsorption at the interface. Here we use coarse-grained molecular-dynamics simulations to consider a number of related issues by calculating the interfacial tension in protein-free lipid droplets, and in HDL and LDL particles mimicking physiological conditions. First, our results suggest that the curvature dependence of interfacial tension becomes significant for particles with a radius of ∼5 nm, when the area per molecule in the surface region is <1.4 nm(2). Further, interfacial tensions in the used HDL and LDL models are essentially unaffected by single apo-proteins at the surface. Finally, interfacial tensions of lipoproteins are higher than in thermodynamically stable droplets, suggesting that HDL and LDL are kinetically trapped into a metastable state.

Details

Authors
  • Samuli Ollila
  • Antti Lamberg
  • Maria Lehtivaara
  • Artturi Koivuniemi
  • Ilpo Vattulainen
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biophysics
Original languageEnglish
Pages (from-to)1236-1244
JournalBiophysical Journal
Volume103
Issue number6
Publication statusPublished - 2012
Publication categoryResearch
Peer-reviewedYes