Iron—sulfur proteins vibrational modes

In oxidized Rieske proteins, a larger number of peaks are observed that have been attributed to vibrations of the iron-sulfur core this is indicative of the reduced symmetry of the iron-sulfur core in Rieske proteins since ungerade vibrations are Raman-inactive in the centro-symmetric (in first approximation) [2Fe-2S]-Cys4 core (point group D2h or Cih) while the corresponding modes are Raman-active in C2 symmetry. The characteristic peak of the SL mode of proteins con-... 

Synchrotron-based nuclear resonance methods have revealed the vibrational dynamics of the iron atom in numerous systems, including alloys, amorphous materials, nanomaterials, and materials under high pressure. The above-mentioned selectivity for the probe nucleus is particularly valuable for biological macromolecules, which may contain many thousands of atoms, but a localized active site is often the true center of interest. Since its availability, NRVS has been applied to study the vibrational dynamics of Fe in proteins, porphyrin model compounds, " and iron-sulfur clusters. It is shown that NRVS can provide frequencies, amplitudes, and directions for Fe vibrations in the samples. It helps to clarify mode assignments in vibrational spectra and reveals many important vibrational modes of Fe that cannot be seen by other methods. In particular, NRVS reveals low-frequency motions of the Fe down to below 100 cm that control biological reactions. The applications presented here use Fe as the probe nucleus, but the principle applies to other Mossbauer isotopes such as " Sn, Kr, Ni, and Zn if appropriate sources are available. 

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