Mössbauer Spectroscopy in the Energy and in the Time Domain, a Crucial Tool for the Investigation of Protein Dynamics

Author： Huenges Alexandra Achterhold Klaus Parak Fritz

ISSN： 0304-3843

Source： Hyperfine Interactions, Vol.144, Iss.1-4, 2002-12, pp. : 209-222

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

New experiments on MbCO crystals and MbCO in a glycerol/water solution are described. Phonon-assisted Mössbauer effect reveals solid state like harmonic vibrations and is used to determine the phonon density of states spectrum at the iron center of myoglobin. Above 200 K, a new type of fluctuations arises which is essential for protein function. The experiments can be explained by a two state model. In the “rigid” state, harmonic vibrations are present in the full temperature regime. Above 200 K a “flexible” state can be reached. The quasi-diffusive motions in this state can be described by an overdamped Brownian oscillator with only one frequency. The Boltzmann probability to reach the flexible state is used. The influence of the solvent surrounding the protein is investigated. The dynamical transition temperature of the protein is compared with a glass transition.