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

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Interfacial tension and surface pressure of high density lipoprotein, low density lipoprotein, and related lipid droplets. / Ollila, Samuli; Lamberg, Antti; Lehtivaara, Maria; Koivuniemi, Artturi; Vattulainen, Ilpo.

In: Biophysical Journal, Vol. 103, No. 6, 2012, p. 1236-1244.

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Ollila, Samuli ; Lamberg, Antti ; Lehtivaara, Maria ; Koivuniemi, Artturi ; Vattulainen, Ilpo. / Interfacial tension and surface pressure of high density lipoprotein, low density lipoprotein, and related lipid droplets. In: Biophysical Journal. 2012 ; Vol. 103, No. 6. pp. 1236-1244.

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TY - JOUR

T1 - Interfacial tension and surface pressure of high density lipoprotein, low density lipoprotein, and related lipid droplets.

AU - Ollila, Samuli

AU - Lamberg, Antti

AU - Lehtivaara, Maria

AU - Koivuniemi, Artturi

AU - Vattulainen, Ilpo

PY - 2012

Y1 - 2012

N2 - 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.

AB - 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.

U2 - 10.1016/j.bpj.2012.08.023

DO - 10.1016/j.bpj.2012.08.023

M3 - Article

VL - 103

SP - 1236

EP - 1244

JO - Biophysical Journal

JF - Biophysical Journal

SN - 1542-0086

IS - 6

ER -