This project is directed towards a wider understanding of resolved fluorescence spectroscopy as applied to proteins and towards answering specific questions about the heme proteins, cytochrome c and horse-radish peroxidase. Using the conditions of site selection fluorescence, line-narrowed emission spectra can be obtained from iron-free or metal- substituted derivatives of these heme proteins. Specific emphasis will be placed on the role of the protein in stabilizing deformations of the porphyrin induced by Jahn- Teller instability. The distribution of protein substates will also be studied. Evidence that proteins undergo considerable intramolecular motion comes from a variety of experimental observations which have been interpreted in terms of conformational fluctuations of the polypeptide chain. In addition to structural substates, there may be "chemical" substates arising because proteins are polyelectrolytes. Whether the origin of the substates is structural or chemical, each substate will have unique physical and chemical properties. The use of fluorescence line narrowing spectroscopy will enable the characterization of the substates in heme proteins.
