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Interfacial Properties of High-Density Lipoprotein-like Lipid Droplets with Different Lipid and Apolipoprotein A-I Compositions

Koivuniemi, Artturi; Sysi-Aho, Marko; Oresic, Matej and Ollila, Samuli LU (2013) In Biophysical Journal 104(10). p.2193-2201
Abstract
The surface properties of high-density lipoproteins (HDLs) are important because different enzymes bind and carry out their functions at the surface of HDL particles during metabolic processes. However, the surface properties of HDL and other lipoproteins are poorly known because they cannot be directly measured for nanoscale particles with contemporary experimental methods. In this work, we carried out coarse-grained molecular dynamics simulations to study the concentration of core lipids in the surface monolayer and the interfacial tension of droplets resembling HDL particles. We simulated lipid droplets composed of different amounts of phospholipids, cholesterol esters (CEs), triglycerides (TGs), and apolipoprotein A-Is. Our results... (More)
The surface properties of high-density lipoproteins (HDLs) are important because different enzymes bind and carry out their functions at the surface of HDL particles during metabolic processes. However, the surface properties of HDL and other lipoproteins are poorly known because they cannot be directly measured for nanoscale particles with contemporary experimental methods. In this work, we carried out coarse-grained molecular dynamics simulations to study the concentration of core lipids in the surface monolayer and the interfacial tension of droplets resembling HDL particles. We simulated lipid droplets composed of different amounts of phospholipids, cholesterol esters (CEs), triglycerides (TGs), and apolipoprotein A-Is. Our results reveal that the amount of TGs in the vicinity of water molecules in the phospholipid monolayer is 25-50% higher compared to the amount of CEs in a lipid droplet with a mixed core of an equal amount of TG and CE. In addition, the correlation time for the exchange of molecules between the core and the monolayer is significantly longer for TGs compared to CEs. This suggests that the chemical potential of TG is lower in the vicinity of aqueous phase but the free-energy barrier for the translocation between the monolayer and the core is higher compared to CEs. From the point of view of enzymatic modification, this indicates that TG molecules are more accessible from the aqueous phase. Further, our results point out that CE molecules decrease the interfacial tension of HDL-like lipid droplets whereas TG keeps it constant while the amount of phospholipids varies. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biophysical Journal
volume
104
issue
10
pages
2193 - 2201
publisher
Cell Press
external identifiers
  • wos:000319318400013
  • scopus:84878145911
ISSN
1542-0086
DOI
10.1016/j.bpj.2013.02.058
language
English
LU publication?
yes
id
e1c068b3-39e9-4f53-bff0-2c934da54eeb (old id 3931638)
date added to LUP
2013-07-15 14:01:43
date last changed
2019-03-31 03:20:16
@article{e1c068b3-39e9-4f53-bff0-2c934da54eeb,
  abstract     = {The surface properties of high-density lipoproteins (HDLs) are important because different enzymes bind and carry out their functions at the surface of HDL particles during metabolic processes. However, the surface properties of HDL and other lipoproteins are poorly known because they cannot be directly measured for nanoscale particles with contemporary experimental methods. In this work, we carried out coarse-grained molecular dynamics simulations to study the concentration of core lipids in the surface monolayer and the interfacial tension of droplets resembling HDL particles. We simulated lipid droplets composed of different amounts of phospholipids, cholesterol esters (CEs), triglycerides (TGs), and apolipoprotein A-Is. Our results reveal that the amount of TGs in the vicinity of water molecules in the phospholipid monolayer is 25-50% higher compared to the amount of CEs in a lipid droplet with a mixed core of an equal amount of TG and CE. In addition, the correlation time for the exchange of molecules between the core and the monolayer is significantly longer for TGs compared to CEs. This suggests that the chemical potential of TG is lower in the vicinity of aqueous phase but the free-energy barrier for the translocation between the monolayer and the core is higher compared to CEs. From the point of view of enzymatic modification, this indicates that TG molecules are more accessible from the aqueous phase. Further, our results point out that CE molecules decrease the interfacial tension of HDL-like lipid droplets whereas TG keeps it constant while the amount of phospholipids varies.},
  author       = {Koivuniemi, Artturi and Sysi-Aho, Marko and Oresic, Matej and Ollila, Samuli},
  issn         = {1542-0086},
  language     = {eng},
  number       = {10},
  pages        = {2193--2201},
  publisher    = {Cell Press},
  series       = {Biophysical Journal},
  title        = {Interfacial Properties of High-Density Lipoprotein-like Lipid Droplets with Different Lipid and Apolipoprotein A-I Compositions},
  url          = {http://dx.doi.org/10.1016/j.bpj.2013.02.058},
  volume       = {104},
  year         = {2013},
}