Table 1.
Initial-Rate Parameters for WT and Spin-Labeled SULT2B1b Mutants
| Enzyme1 | kcat (s−1)2 | Km 1-HP (μM)2 | Ki Quc (μM)3 |
|---|---|---|---|
| WT | 3.4 (0.2)4 | 3.8 (0.3) | 0.32 (0.2) |
| NR5 | 3.3 (0.2) | 3.5 (0.2) | 0.30 (0.2) |
| 216 | 3.6 (0.3) | 4.2 (0.3) | 0.33 (0.1) |
| 171 | 3.0 (0.2) | 4.1 (0.2) | 0.35 (0.2) |
| 247 | 3.5 (0.3) | 3.6 (0.3) | 0.32 (0.2) |
1
All constructs contain the phosphomimetic mutation (S347D).
2
kcat and Km were determined at saturating PAPS (300 μM, 910 × Km).
3
Ki Quc was determined at saturating PAPS (300 μM, 910 × Km) and 1-HP (100 μM, 26 × Km).
4
Values in parentheses indicate one standard deviation.
5
NR, non DTNB-reactive scaffold (SULT2B1b C81S, C225S, C278S, S347).
6
Number indicates residue at which Cys is knocked in and the spin label is attached.