AB-INITIO STUDIES ON THE FE-S PROTEIN MODEL COMPLEXES

In this paper, ab initio calculations of the iron-sulfur protein model complexes have been completed on Fe2S2(SH)4n- and Fe4S4(SH)4n- (n = 2 , 3). The results indicate that the occupied terminal sulfur character istic orbitals are found in the front orbital site and the energy leve ls of the occupied Fe 3d-like orbitals appear internally below the S-H bonding orbitals in the valence band. Although the energy sequence is different from what was reported in literature, our results are in ag reement with the relevant experimental facts. We have discussed the re ason that variations of the active sites are produced by various oxida tion levels. The action mechanism of the Fe-S proteins as electron car riers in the biological processes is also explored preliminarily.