| Autor: |
More, Claude, Camensuli, Philippe, Dole, François, Guigliarelli, Bruno, Asso, Marcel, Fournel, André, Bertrand, P. |
| Zdroj: |
Journal of Biological Inorganic Chemistry (JBIC); Apr1996, Vol. 1 Issue 2, p152-161, 10p |
| Abstrakt: |
The quantitative analysis of intercenter magnetic interactions, based on the simulation of EPR spectra recorded at different microwave frequencies, is a powerful technique to determine the relative arrangement of paramagnetic centers in metalloproteins. Such simulations generally rely on a model Hamiltonian in which the interacting centers are approximated by point dipoles. This approximation is often sufficient when these centers are mononuclear metal complexes or organic radicals in which the spin density is not too delocalized and keeps a constant sign. It is used in the present paper to study the magnetic interactions among several hemes and between a heme and a FMN radical in cytochromes. In the case of metalloproteins containing polynuclear metal clusters, the point dipole approximation is no longer valid and must be replaced by a local spin model in which the magnetic interactions among all the paramagnetic sites of the system are explicitly considered. Numerical simulations based on this model provide a description of the relative arrangement of the interacting centers at atomic resolution and can be used to assign a valence state to the different metal ions of the clusters. This is illustrated by recent studies carried out on metalloproteins containing [2Fe-2S] and [4Fe-4S] clusters. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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