title: Spectral diffusion and the energy landscape of a protein.
abstract: We present a novel type of spectral diffusion experiment in the millikelvin range to characterize the energy landscape of a protein as compared with that of a glass. We measure the time evolution of spectral holes for more than 300 hr after well-defined initial nonequilibrium conditions. We show that the model of noninteracting two-level systems can describe spectral diffusion in the glass, but fails for the protein. Our results further demonstrate that randomness in the energy landscape of a protein shows features of organization. There are "deep minimum" states separated by barriers, the heights of which we are able to estimate. The energy landscape of a glass is featureless by comparison.
authors.affiliation: Physikalisches Institut, Universität Bayreuth, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Fritsch
authors.forename: J
authors.initials: J
authors.lastname: Friedrich
authors.forename: F
authors.initials: F
authors.lastname: Parak
authors.forename: J L
authors.initials: JL
authors.lastname: Skinner
mesh_terms: D004058:Diffusion; D008961:Models, Structural; D009211:Myoglobin / Q000737:chemistry*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D011524:Protoporphyrins; D013053:Spectrophotometry
chemical_list: D009211:Myoglobin; D011506:Proteins; D011524:Protoporphyrins; C028025:protoporphyrin IX