Table 4. Select Structural Properties of Peroxodiferric Active Sites from XRD and XAS Studies.
| enzyme | K-edge (eV) [pre-edge area] | Fe···Fe (Å)a | bridging units (νO–O by rR) | PDB ID (res. in Å) | refs |
|---|---|---|---|---|---|
| Hr | 7124.3 [16.9]b | 3.3 (XRD) 3.24 (XAS) | μ-oxo-bis(μ-1,3-O2CR) (η1-OOH) | 1HMO (2.0) | 18 |
| W48A/D84E RNR R2 | 2.5 (XAS) | μ-1,2-peroxo- bis(μ-1,1-O2CR) | 38 | ||
| W48F/D84E RNR R2 | 3.8 (DFT based on rR data) | μ-1,2-peroxo- bis(μ-1,3-O2CR) (870 cm−1) | 38,41,110 | ||
| ferroxidase site of frog M ferritin | 7124 [13.3] | 2.53 | μ-1,2-peroxo- bis(μ-1,1-O2CR) (851 cm−1) | 50 | |
| ferroxidase site of human L ferritin | 3.2–3.5 | μ3-oxo-μ-1,2-peroxo-μ-1,3-O2CR | 5LG8 (1.98) | 114 | |
| T4MOH/D (Pμ1,2) | 3.4 | μ-1,2-peroxo- μ-1,3-O2CR μ-solvato | 3I63 (2.09) | 115 | |
| T4MOH/D (Pμ1,1) | 3.2 | μ-1,1-(hydro)peroxo- μ-1,1-O2CR μ-1,3-O2CR | 5TDV (2.0) | 70 | |
| T4MOH/D (Pη22) | 3.3 | μ–η2:η2-OOR- μ-solvato | 5TDT (1.82) | 70 | |
| hDOHH | 7125.6 [12.4] | 3.8 (3.7) 3.41 | μ-hydroxo-μ-1,2-peroxo (855 cm−1) | 4D50 (1.7) | 16,67 |
| CmlI | 7124.9 [19.2] | 3.35 | μ-oxo-μ-1,1-peroxo-μ-1,3-O2CR (791 cm−1) | 64 | |
| CmlI | 3.3 | μ-1,2-peroxo-μ-1,3-O2CR | 5HYG (2.03) | 63 |
a
Information on Fe···Fe distance derived from XAS indicated in italics.
b
See Figure S1