TABLE 3.
Optically active and paramagnetic intermediates of DHP A and DHP B (and their mutants) formed upon activation by H2O2 at pH 7
| Protein | Compound I λmaxa | Compound II λmaxa | Protein bound radical concluded to be on residueb | Final observed species λmaxc |
|---|---|---|---|---|
| nm | nm | nm | ||
| DHP A (WT) | Not detected | 420, 545, 585 | Tyr-34 (mj); Tyr-38 (mn) | 411, 530, 564 (DHP A Compound RH) |
| DHP A (Y34F) | Not detected | 419, 545, 584 | Tyr-38 | 416, 560, 598 (Compound RH-like) |
| DHP A (Y38F) | Not detected | 419, 545, 585 | Tyr-34 | 418, 543, 578 (Compound III)d |
| DHP A (Y34F/Y38F) | 405, 505 (br sh), 643 | 414, 505, (sh), 540, 589 (sh) (Compound I/II mixture) | Tyr-28 | Bleached |
| DHP B (WT) | Not detected | 419, 545, 585 | Tyr-38 (mj); Tyr-28 (mn) | 411, 554, 599 (DHP B Compound RH) |
| DHP B (Y28F) | Not detected | 419, 545, 584 | Tyr-38 | 415, 552, 598 (Compound RH-like) |
| DHP B (Y38F) | 405, 520, 644 | 411, 518, 540 (sh), 587 (sh) (Compound I/II mixture) | Tyr-28 | Bleached |
| DHP B (Y28F/Y38F) | 406, 528, 645 | Not detected | Not detected | 404, 518, 542 (sh)d |
a sh indicates “shoulder,” and br sh indicates “broad shoulder.”
b mj indicates “major,” and mn indicates “minor” (free radical species).
c After 85 s.
d Slight bleaching was also observed.