Static and dynamic properties of phospholipid bilayer nanodiscs.
Nanodiscs are phospholipid-protein complexes which are relevant to nascent high-density lipoprotein and are applicable as a drug carrier and a tool to immobilize membrane proteins. We evaluated the structure and dynamics of the nanoparticles consisting of dimyristoylphosphatidylcholine (DMPC) and apolipoprotein A-I (apoA-I) with small-angle neutron scattering (SANS) and fluorescence methods and compared them with static/dynamic properties for large unilamellar vesicles. SANS revealed that the nanodisc includes a lipid bilayer with a thickness of 44 A and a radius of 37 A, in which each lipid occupies a smaller area than the reported molecular area of DMPC in vesicles. Fluorescence measurements suggested that DMPC possesses a lower entropy in nanodiscs than in vesicles, because apoA-I molecules, which surround the bilayer, force closer lipid packing, but allow water penetration to the acyl chain ends. Time-resolved SANS experiments revealed that nanodiscs represent a 20-fold higher lipid transfer via an entropically favorable process. The results put forward a conjunction of static/dynamic properties of nanodiscs, where the entropic constraints are responsible for the accelerated desorption of lipids.
Nakano
Minoru
M
Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. mnakano@pharm.kyoto-u.ac.jp
Fukuda
Masakazu
M
Kudo
Takayuki
T
Miyazaki
Masakazu
M
Wada
Yusuke
Y
Matsuzaki
Naoya
N
Endo
Hitoshi
H
Handa
Tetsurou
T
D016632:Apolipoprotein A-I / Q000737:chemistry* / Q000648:ultrastructure; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D015394:Molecular Structure; D049329:Nanostructures / Q000648:ultrastructure*; D009502:Neutrons; D053838:Scattering, Small Angle
D016632:Apolipoprotein A-I; D008051:Lipid Bilayers; D004134:Dimyristoylphosphatidylcholine