A full understanding of protein function requires detailed knowledge of the relation between structural and dynamic properties. Myoglobin (Mb), a ligand-binding heme protein, has served as a model system for the experimental and theoretical study of protein dynamics and their relation to structure. This research will employ femtosecond time-resolved IR spectroscopy to characterize the following dynamical processes in Mb: 1. Conformational relaxation of the heme after dissociation of a ligand. 2. Geminate recombination of ligands with the heme. 3. Motion of the ligand within the protein. These studies should identify the mechanisms that influence the rate of ligand binding. In addition, the experimental measurements of the motional dynamics of ligands may be used to refine molecular dynamics simulations; realistic simulations would establish the connection between structure and dynamics. These studies will employ a time-resolved IR spectrometer that provides unprecedented sensitivity and approximately 350 fs time resolution. The conformational relaxation of the heme and the rate of geminate recombination will be probed via band III, a deoxyheme. The motional dynamics of infrared-active ligands (e.g. CO and NO) will be characterized via their IR absorption spectrum.
