Fritsch K, Friedrich J, Parak F, Skinner JL. Spectral diffusion and the energy landscape of a protein.
Proc Natl Acad Sci U S A 1996;
93:15141-5. [PMID:
8986777 PMCID:
PMC26370 DOI:
10.1073/pnas.93.26.15141]
[Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/1996] [Accepted: 10/10/1996] [Indexed: 02/03/2023] Open
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.
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