title: Static and dynamic properties of phospholipid bilayer nanodiscs.
abstract: 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.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. mnakano@pharm.kyoto-u.ac.jp
authors.forename: Minoru
authors.initials: M
authors.lastname: Nakano
authors.forename: Masakazu
authors.initials: M
authors.lastname: Fukuda
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kudo
authors.forename: Masakazu
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Wada
authors.forename: Naoya
authors.initials: N
authors.lastname: Matsuzaki
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endo
authors.forename: Tetsurou
authors.initials: T
authors.lastname: Handa
mesh_terms: 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
chemical_list: D016632:Apolipoprotein A-I; D008051:Lipid Bilayers; D004134:Dimyristoylphosphatidylcholine