(228z) Designer Bicelles: Peptoid Incorporation into the Edges and the Planar Region

Authors: 
Najafi, H., University of Arkansas
Servoss, S., University of Arkansas
The study of membrane-affiliated interactions is significant to the understanding of cell function, detecting biomarkers to diagnose disease, and testing the efficiency of new therapeutic targets. The amphiphilic character of membrane proteins makes them difficult to work with due to low stability. Model membrane systems can be used to stabilize membrane protein structure and maintain native activity. The model membrane system of focus in this study are bicelles, disc-shaped lipid bilayers created by combining long- and short-chain phospholipid pairs. We have modified the chemistry at the edges and at the planar region of bicelles by incorporating peptoids, which are non-natural protein mimics. Peptoids are ideal for this application since a large diversity of side chains can be easily incorporated in a sequence-specific manner. In these preliminary studies two sequence of peptoids were designed to contain a lipophilic side chain at the C-terminus for interactions with the short and long-chain lipid tail groups to for the edge and planar modification, respectively as well as thiol groups at the N-terminus for characterization. Peptoid-bicelles were imaged using transmission electron microscopy and size analysis was performed by dynamic light scattering. The presence of peptoids in the edges and planar regions of the bicelles was confirmed by attachment of gold nanoparticles to the thiol groups within the peptoid sequence. Our results show that the designed peptoids incorporate preferentially into the edges and planar regions of the bicelles, respectively as expected. Further studies will be performed to alter the diameter of the bicelles to allow for study of membrane proteins and complexes of various sizes.
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