PEPTIDE/LIPID STUDIES IN FIELD ORIENTED MEMBRANES

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DESCRIPTION (Adapted from applicant's abstract): Despite the abundance and clear importance of membrane-bound molecules, there is a dramatic lack of high resolution structural data on membrane systems. The overall goals of this research are the development and testing of new methodology that is capable of providing atomic level structural and dynamic information on membrane-bound proteins in a lipid bilayer. The methods utilize phospholipid bilayer arrays that spontaneously orient in magnetic fields and allow for high resolution spectroscopy in a model for a natural membrane. These methods will be applied to model transmembrane helical peptides: one of the fundamental structural motifs found in membrane proteins. Transmembrane helices have been shown to have many important functions, including defining channels and transport pathways, positioning prosthetic groups for electron transfer reactions, and mediating transmembrane signaling. The first step in the study will be to optimize the magnetic field orientable lipid bilayers for novel nuclear magnetic resonance (NMR) studies of transmembrane peptides. Next, the order and orientation of specific peptides in a model membrane helix will be determined using 2H NMR spectroscopy. Finally, information about the interaction of the transmembrane peptides with the surrounding lipid bilayer will be measured using both oriented 2H NMR and novel oriented electron spin resonance (ESR) experiments. Investigations of prototypal transmembrane helices will not only help establish the feasibility of the magnetic orientation methodology, but will also answer some of the basic questions that surround the properties of transmembrane helices, as well as their interactions with lipid bilayers. Although the studies proposed here are for single transmembrane helices, this work will pave the way for studies of larger fragments and intact membrane proteins.