Technique for Extraction of Membrane Proteins

In a new study, researchers focused on problems of drug delivery through cell membranes describe the development of a technique for the extraction of membrane-bound proteins in a way that permits examining their folding and unfolding within lipid bilayers of different composition.

Investigators at the University of Virginia (Charlottesville, USA) used an aqueous system containing urea to extract the outer membrane protein A from Escherichia coli. The protein extracted in this fashion was able to fold and unfold reversibly in a model bilayer made from palmitoyl-oleoyl-phosphatidylcholine and palmitoyloleoyl-phosphatidylglycerol. Results reported in the March 23, 2004, issue of the Proceedings of the [U.S.] National Academy of Sciences indicated that folding was a two-state process with free energy of 3.4 kcal/mol.

"The majority of drugs on the market today are effective because they work on membrane proteins, but our basic knowledge about these proteins lags far behind that of water-soluble proteins,” explained senior author Dr. Lukas Tamm, professor of molecular physiology and biologic physics at the University of Virginia. "This protocol developed at the University of Virginia shows for the first time that these proteins can be taken out of their membrane environment and put back in without losing function.”




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