Structural characterization of styrene-maleic acid copolymer-lipid nanoparticles (SMALPs) using EPR spectroscopy.

Spectroscopic studies of membrane proteins (MPs) are challenging due to difficulties in preparing homogenous and functional lipid membrane mimetic systems into which membrane proteins can properly fold and function. It has recently been shown that styrene-maleic acid (SMA) copolymers act as a macromolecular surfactant and therefore facilitate the formation of disk-shaped lipid bilayer nanoparticles (styrene-maleic acid copolymer-lipid nanoparticles (SMALPs)) that retain structural characteristics of native lipid membranes. We have previously reported controlled synthesis of SMA block copolymers using reversible addition-fragmentation chain transfer (RAFT) polymerization, and that alteration of the weight ratio of styrene to maleic acid affects nanoparticle size.

Characterization of the structure of lipodisq nanoparticles in the presence of KCNE1 by dynamic light scattering and transmission electron microscopy.

A recently developed membrane mimetic system called styrene maleic acid lipid particles (SMALPs) or lipodisq nanoparticles has shown to possess significant potential for biophysical studies of membrane proteins. This new nanoparticle system is composed of lipids encircled by SMA copolymers. Previous studies showed that SMA copolymers are capable of extracting membrane proteins directly from their native environments without the assistance of detergents.

Development of electron spin echo envelope modulation spectroscopy to probe the secondary structure of recombinant membrane proteins in a lipid bilayer.

Membrane proteins conduct many important biological functions essential to the survival of organisms. However, due to their inherent hydrophobic nature, it is very difficult to obtain structural information on membrane-bound proteins using traditional biophysical techniques. We are developing a new approach to probe the secondary structure of membrane proteins using the pulsed EPR technique of Electron Spin Echo Envelope Modulation (ESEEM) Spectroscopy.