Myoglobin Mossbauer spectroscopy

Apart from fluorescence, several other methods may be used to obtain time-resolved information. In the case of proteins containing an iron atom, Mossbauer spectroscopy allows the determination, in the iron binding site, of not only root-mean-square shifts of atoms but also the times over which such shifts occur. Detailed investigations of myoglobin have yielded relaxation times on the order of 10 8 Proton NMR spectroscopy can be used to... 

Figure 4.2. Temperature dependence of the rate constant of electron transfer (Icet) in myoglobin modified covalently by donor-acceptor groups (a) and the deviation of various dynamic quantities from normal harmonic behaviour obtained by molecular dynamic simulation, inelastic neutron scattering, MOssbauer spectroscopy and spectral broadening analysis (b). (Likhtenshtein et al., 2000). Reproduced with permission.

Fig. 25. Mean square displacements, in myoglobin as a function of temperature. X-Ray structure analysis 9, iron V, histidine (HisFS) bound to the iron 0, distal histidine (HisE7) ---—, linear regression —, extrapolation. Mossbauer spectroscopy O,...

At low temperatures, each protein is trapped in a particular conformational substate, and dynamics are nearly harmonic. Qualitatively different dynamical behavior appears above a dynamical transition near 180 K, where the mean square displacement of the Fe atom in myoglobin, as determined using Mossbauer spectroscopy, strongly deviates from a harmonic extrapolation of low-temperature behavior " (Fig. 5j. Hydrogen fluctuations... 

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