Table 7.

Averages (avg) of the Calculated Fe-Fe and Fe-ligand Bond Lengths (Å), Broken-Symmetry State Energies (E, eV), and Reduction Potentials of the [Fe₄S₄(S_γ-Cys)₄]²⁻/[Fe₄S₄(S_γ-Cys)₄]³⁻ (2−/3−) Quantum Clusters with Substrate and without Substrate Binding in Wild-type, No-tandem and K144A Models.

	Chain-A without APS
	Wild-type		No-tandem		K144A
	2−	3−	2−	3−	2−	3−
6(Fe-Fe)avg	2.690	2.697	2.711	2.718	2.704	2.698
4(Fe-S)avg a	2.228	2.253	2.229	2.258	2.223	2.253
8(Fe-S)avg b	2.318	2.334	2.326	2.333	2.329	2.335
4(Fe-Sγ)avg	2.285	2.333	2.299	2.341	2.289	2.329
E	−1193.735	−1196.724	−1185.564	−1188.659	−1135.356	−1138.287
E0	−1.35		−1.25		−1.41
	Chain-B with APS
	Wild-type		No-tandem		K144A
	2−	3−	2−	3−	2−	3−
6(Fe-Fe)avg	2.715	2.718	2.728	2.724	2.714	2.706
4(Fe-S)avg a	2.207	2.239	2.217	2.242	2.209	2.242
8(Fe-S)avg b	2.304	2.308	2.303	2.308	2.306	2.311
4(Fe-Sγ)avg	2.286	2.327	2.289	2.338	2.282	2.319
E	−1446.545	−1449.460	−1438.362	−1441.410	−1387.923	−1390.710
Eo	−1.43		−1.29		−1.55

^aThe average of the following four Fe-S distances: Fe1-S3, Fe2-S4, Fe3-S1, and Fe4-S2 (see Figure 5).

^bThe average of the following eight Fe-Fe distances: Fe1-S1, Fe1-S2, Fe2-S1, Fe2-S2, Fe3-S3, Fe3-S4, Fe4-S3, and Fe4-S4.