Membrane proteins account for approximately 30% of the entire human genome and over 50% of current drug targets. Since membrane proteins exhibit a variety of functions crucial to the survival of organisms, it is imperative that their structure and dynamics be understood. However, one of the difficulties with spectroscopic studies of membrane proteins is in the preparation of homogenous and functional lipid membrane systems into which these membrane proteins can be incorporated. While traditional membrane systems such as micelles or liposomes can be highly useful, there are major limitations for their use in membrane protein studies. Spherical micelle complexes do not form lipid bilayers, while liposomes are difficult to produce homogenously in solution. Recently, a new nano-sized polymer ring was developed to serve as a better membrane mimetic. Using styrene maleic anhydride (SMA) polymers, homogenous nano-sized disk-like particles can be formed that retain a lipid bilayer structure. While these nano-rings are indeed a promising membrane mimetic, they have yet to be fully structurally characterized, and the interactions between the lipid bilayer and the solubilized SMA polymer are currently not fully understood. In this study, EPR spectroscopy will be used to detect the perturbation on the aceyl chain upon introduction of the SMA polymer by attaching PC-based nitroxide spin labels to different positions along the aceyl chain. This study will aid in determining the feasibility of the nano-rings as a protein-incorporated membrane mimetic and will provide significant information on the structural and dynamic properties of a potentially physiologically relevant membrane mimetic system. Development of a more native-like and experimentally practical membrane mimetic will notably improve membrane protein studies, and will contribute to a better understanding of membrane protein structure and dynamics.

Probing the structure of new membrane-mimetic lipid nano-rings using continuous-wave EPR spectroscopy

251st National Meeting (2016)

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