The energetics governing the folding and function of membrane proteins is less well understood than for water-soluble ones. Thus, while there are abundant data concerning the free energy associated with the burial of an apolar group or the formation of a hydrogen bond in water-soluble proteins, such data are virtually non-existent for membrane proteins. We will determine how amino acid substitutions in the membrane protein bacteriorhodopsin affect its free energy of stabilization. It has been hypothesized that although water-soluble and membrane proteins differ greatly in the polarity of water-facing versus membrane lipid-facing residues, their interior side-chain packing and residue polarities are highly similar. To test this guiding hypothesis we will convert water-soluble proteins into membrane-soluble proteins and vice versa.
Our specific aims, then, are: - Aim 1. Membrane-soluble versions of the water-soluble coiled-coil peptide, GCN4-P1, will be designed, synthesized and characterized in micelles and bilayers. - Aim 2. We will determine the effect of amino acid substitutions on the thermodynamic stability of bacteriorhodopsin. - Aim 3. We will design and characterize a water-soluble version of phospholamban, a 57-residue membrane protein that forms transmembrane pentamers. In each case, the thermodynamic properties of the proteins will be thoroughly examined to provide a deeper, quantitative understanding of membrane protein structure.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM060610-02
Application #
6387072
Study Section
Biophysical Chemistry Study Section (BBCB)
Program Officer
Wehrle, Janna P
Project Start
2000-09-30
Project End
2004-08-31
Budget Start
2001-09-01
Budget End
2002-08-31
Support Year
2
Fiscal Year
2001
Total Cost
$272,624
Indirect Cost
Name
University of Pennsylvania
Department
Biochemistry
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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