Table 1.
Extended X-ray Absorption Fine Structure (EXAFS) Curve-Fitting Parameters for Fe K-edge. Coordination Number (N), Interatomic Distances (R), Mean-Square Deviations in Interatomic Distance (σ2, Å2), Fit-Error Function (F) is Defined as <{Σk6 (χcalc* – χexpt)2 / Σχ2expt}1/2>. For Mt-APSR the k Range was 2.35 ~ 17 (Filtered R = 1.2 ~ 3); for Mt-APSR + APS the k Range was 2.15 ~ 17 (Filtered R = 1.2 ~ 3); giving resolution ~ 0. 1 Å and ~17 independent degrees of freedom. Fits are shown both for fixed (marked with *) and variable N
| Sample | Interaction | N | R (Å) | σ2 × 103 | F |
|---|---|---|---|---|---|
| Mt-APSR | Fe-S | 4* | 2.297 | 3.9 | 1.93 |
| sample 1 | Fe-Fe | 3* | 2.726 | 2.4 | |
| Fe-S | 3.9 | 2.297 | 3.8 | 1.92 | |
| Fe-Fe | 2.1 | 2.726 | 2.7 | ||
| Mt-APSR | Fe-S | 4* | 2.294 | 3.9 | 1.92 |
| sample 2 | Fe-Fe | 3* | 2.729 | 2.0 | |
| Fe-S | 3.7 | 2.294 | 3.4 | 1.86 | |
| Fe-Fe | 1.7 | 2.729 | 1.3 | ||
| Mt-APSR + APS a | Fe-S | 4* | 2.298 | 3.9 | 1.28 |
| sample 1 | Fe-Fe | 3* | 2.728 | 2.2 | |
| Fe-S | 3.8 | 2.298 | 3.6 | 0.93 | |
| Fe-Fe | 2.0 | 2.728 | 2.2 | ||
| Mt-APSR + APS a | Fe-S | 4* | 2.297 | 3.8 | 1.48 |
| sample 2 | Fe-Fe | 3* | 2.730 | 2.5 | |
| Fe-S | 3.6 | 2.297 | 3.4 | 1.44 | |
| Fe-Fe | 1.8 | 2.730 | 2.0 | ||
a
The enzyme was in the S-sulfocysteine state with AMP bound and the C-terminal docked in the active site.