Polymer stabilised phospholipid nanodiscs

Abstract

Membrane proteins are involved in several fundamental biological processes such astransport or signal transduction. Most of them are enzymes, receptors or otherimportant biological macromolecules representing up to 70% of therapeutic targets.Despite the interest in understanding their structures and behaviour the scientificknowledge is still very limited due to several practical difficulties. In 2009 a newplatform for membrane protein studies called SMALP (Styrene-Maleic Acid LipidParticles) nanodiscs was introduced. SMALPs are self-assembled structures formedby a bilayer of phospholipids controlled in diameter by a polystyrene maleic acid(SMA) copolymer belt.The purpose of this research project herein presented was to structurally characteriseSMALPs, with analyses aimed to understand the role of both the polymeric and lipidparts in the self-assembly process. A series of investigations were carried out toelucidate the specific copolymer characteristics that allow the assembly into suchwell-defined, stable and reproducible structures. Experiments performed via smallangle X-ray (SAXS) and neutron (SANS) scattering together with nuclear magneticresonance (NMR), gel-filtration chromatography (GPC), dynamic light scattering(DLS), allowed identification of the specific polymeric characteristics of thecopolymer architecture which were revealed to be crucial for the SMALPs assemblyprocess.Investigations performed also addressed the question whether it was possible toassemble nanodiscs with the use of different phospholipids (with different chainlength and charged or non-charged heads) and what the impact of the different lipidshad on the structures.Finally, further analyses were made to test the physical chemical behaviour of theSMALPs when important environmental parameters such as temperature, pH and saltconcentration of the buffer were changed.

Date of Award	9 Dec 2014
Original language	English
Awarding Institution	University of Bath
Sponsors	Science and Technology Facilities Council
Supervisor	Karen Edler (Supervisor), Cameron Neylon (Supervisor) & Stephen Roser (Supervisor)