Table 1.
Bond distances (in Angstroms) for various Cys-bound CDO species as obtained by X-ray crystallography (4JTO) or whole-protein QM/MM optimizations (all other models listed), where X refers to the ligating atom of the sixth ligand present at the Fe center (where applicable). For the analogous Sec-bound analogues, see Table S3 of the Supporting Information
| Species | Fe-NH86 | Fe-NH88 | Fe-NH140 | Fe-SCys | Fe-NCys | Fe-X | Cys-R60, 1 | Cys-R60, 2 | Cys-Y157 |
|---|---|---|---|---|---|---|---|---|---|
| 4JTO, WT (Cys)-Fe(II)CDOa | 1.893 | 2.199 | 2.110 | 2.291 | 2.262 | N/A | N/A | N/A | N/A |
| WT (Cys)-Fe(II)CDO | 2.153 | 2.184 | 2.177 | 2.368 | 2.250 | N/A | 1.800 | 2.014 | 1.537 |
| H155A (Cys)-Fe(II)CDO | 2.158 | 2.198 | 2.172 | 2.372 | 2.256 | N/A | 1.717 | 2.134 | 1.552 |
| H155A (H2O/Cys)-Fe(II)CDO | 2.205 | 2.273 | 2.142 | 2.521 | 2.278 | 2.311 | 1.734 | 2.188 | 1.552 |
| WT (OH−/Cys)-Fe(III)CDO | 2.326 | 2.299 | 2.111 | 2.445 | 2.223 | 1.880 | 1.984 | 1.791 | 1.532 |
| H155A (OH−/Cys)-Fe(III)CDO | 2.328 | 2.287 | 2.116 | 2.428 | 2.237 | 1.872 | 2.110 | 1.717 | 1.549 |
| WT (NO/Cys)-Fe(II)CDO | 2.113 | 2.110 | 2.013 | 2.369 | 2.115 | 1.769 | 1.772 | 2.008 | 1.529 |
| H155A (NO/Cys)-Fe(II)CDO | 2.145 | 2.160 | 2.026 | 2.339 | 2.083 | 1.776 | 1.707 | 2.163 | 1.535 |
a
Crystal structure at 2.00 Å resolution, from Ref 14.