Efforts were directed to gaining an atomic level understanding of how the structural parts of a protein carry out its specific function. Proteins were studied by various techniques such as optical, Raman, electron diffraction and steady-state IR. However, these techniques are incapable of directly monitoring the dynamics of the protein backbone. The technique of picosecond infrared difference spectroscopy which has been developed here with its sensitivity to all parts of the protein and its ultrafast time resolution is an invaluable tool for this purpose. As a test bed for this emerging technology we have used bacteriorhodopsin (bR), from the membrane of Halobacterium halobium. We have investigated the excited electronic states in bR and the dynamics of water molecules buried in the interior of the protein. There is considerable evidence that protein bound water molecules play a role in the proton transfer in bR. We have investigated the time resolved data i n the 350 0-3700 cm-1 region for bR. Techniques are now being developed to probe conformational changes in the far-IR and compare these changes with steady-state measurements being performed at the Brookhaven National Laboratories synchrotron.
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