Table 2.
Design matrix for dependences of PPi exchange. Independent variables are LeuAC (1) or LeuRS (−1), [Leucine] (1,0) potassium flouride (0,1), and enzyme concentration. Dependent variables are the rate of ATP formation and derived quantities: kcat = rate/[Enz], ΔG‡ (kcat) = –RT ln(kcat). The LeuAC2 construct was used as the MBP fusion in these experiments.
| EXPT | LeuAC | Leucine | KF | [Enz], M | Δ[ATP]/Time | kcat (/s) | ΔG‡ (kcat) (Kcal/Mole) |
|---|---|---|---|---|---|---|---|
| 1 | 1 | 0 | 0 | 3.00 × 10−6 | 2.02 × 10−6 | 6.7 × 10−1 | 0.234 |
| 2 | 1 | 0 | 1 | 3.00 × 10−6 | 2.06 × 10−8 | 6.9 × 10−3 | 2.949 |
| 3 | 1 | 1 | 0 | 3.00 × 10−6 | 2.00 × 10−6 | 6.7 × 10−1 | 0.239 |
| 4 | 1 | 1 | 1 | 3.00 × 10−6 | 2.07 × 10−4 | 6.9 × 10−3 | 2.945 |
| 5 | −1 | 0 | 0 | 3.00 × 10−6 | 3.15 × 10−6 | 10.0 | −1.391 |
| 6 | −1 | 0 | 1 | 3.00 × 10−6 | 2.28 × 10−6 | 7.6 | −1.201 |
| 7 | −1 | 1 | 0 | 3.00 × 10−6 | 3.12 × 10−4 | 1.000 | −4.112 |
| 8 | −1 | 1 | 1 | 3.00 × 10−6 | 3.15 × 10-4 | 1.100 | −4.119 |