INFRARED-SPECTROSCOPY OF PROTEINS AND PEPTIDES IN LIPID BILAYERS

Infrared spectroscopy is a useful technique for the determination of c onformation and orientation of membrane-associated proteins and lipids . The technique is especially powerful for detecting conformational ch anges by recording spectral differences before and after perturbations in physiological solution. Polarized infrared measurements on oriente d membrane samples have revealed valuable information on the orientati on of chemical groupings and substructures within membrane molecules w hich is difficult to obtain by other methods. The application of infra red spectroscopy to the static and dynamic structure of proteins and p eptides in lipid bilayers is reviewed with some emphasis on the import ance of sample preparation. Limitations of the technique with regard t o the absolute determination of secondary structure and orientation an d new strategies for structural assignments are also discussed.