Developing Oriented Circular Dichroism Spectroscopy as a Methodological Tool for Characterising Membrane Proteins

Membrane proteins are physiologically-important molecules that are embedded in the phospholipid bilayers surrounding cells. They are the targets of a large number of pharmaceutical drugs because many of them, when mutated, are the causes of diseases. Most methods for examining membrane proteins require that the membranes that surround the proteins be dissolved by detergents, which removes interactions both with each other and with the surrounding lipids that may be important to their functioning. This proposal is to develop a methodological tool that will enable us to examine proteins in intact membranes, thereby preserving their native structure. The method, Oriented Circular Dichroism spectroscopy, would enable the examination of both their local structure and the changes in their structure and orientation associated with how they work.

This is a proposal to develop a methodological tool, oriented circular dichroism spectroscopy, for examining the structure of membrane proteins embedded in phospholipid bilayers and/or 2-dimensional crystals. It would enable the analysis of protein secondary structure and orientation and, importantly, the monitoring of changes in these upon drug and ligand binding, as a means of investigating the dynamic nature and functioning of this class of proteins.

The proposed methodological tool will have potential as a resource for the examination of membrane proteins embedded in phospholipid bilayers, and as a means for examining effects of ligand and drug binding to this class of proteins that play important roles in human health. Whilst this will primarily be a basic science tool, it has potential for application in the pharmaceutical industry as membrane proteins comprise a significant proportion of current drug targets. We have established contracts with a number of companies (pharmaceutical, chemical and SMEs) who access our Dichroweb analysis tool, which demonstrates that CD is a not only a methodology of interest to industry, but one they regularly use; indeed our Dichroweb tool was cited as a high impact case study in the 2007 RCUK Report on the Economic Impact of the Research Councils.