Table 1.
Spectroscopic and binding parameters for the holo-PhuS wild-type and His-mutant proteins.
| Protein (PhuS) | Soret band (nm) | Q-bands (nm) | Spin-state (pH 7.8)* | Proximal His-ligand* | Kd (μM) heme† | KD (μM) heme-PhuS:HemO† |
| Wild type | 411 | 545, 570 | 6CHS/LS | His-209 | 0.41 ± 0.05 | 1.23 ± 0.05 |
| H209A | 410 | 532, 566 | 6CLS | His-212 | 1.6 ± 0.70 | 7.0 ± 0.6 |
| H210A | 412 | 540, 578 | 6CHS/LS | His-209 | 0.48 ± 0.1 | ND |
| H212A | 407 | 544, 580 | 6CHS/5CHS | His-209 | 1.0 ± 0.3 | ND |
| H209/210/212A† | 398, 368 (sh) | 398, 600 | 5CHS | None | 1.2 ± 0.3 | 8.3 ± 0.8 |
ND, no binding observed.
*Previously determined (21).
†Data obtained in the present study as described in Experimental Procedures.