Table 1.
Kinetic parameters for the substrate utilization by E. coli RNAPs (fit to model 1).
| RNAP | Substrate | kon, µM−1 s−1 | koff, s−1 | kcat, s−1 (fast) | kcat, s−1 (slow) | Fast fraction, % | KD, µM |
|---|---|---|---|---|---|---|---|
| WT | GTP | 2.5 (2.2–3.0) | 7.7 (4.0–9.6) | 31 (28–42) | 2.6 (0.8–7.6) | 88 (77–93) | 3.1 (2.3–4.0) |
| WT | 2′dGTP | >0.24 | >45 | 1.4 (1.1–2.3) | 0.35 (0.22–0.49) | 52 (30–70) | 190 (160–220) |
| β′R425K | GTP | 0.5 (0.4–0.8) | 72 (57–120) | 20 (18–25) | 1.3 (0.4–4.1) | 86 (76–92) | 140 (110–160) |
| β′R425K | 2′dGTP | >0.10 | >30 | 13 (11–18) | 2.2 (0.7–5.4) | 78 (50–90) | 420 (330–480) |
| WT | 3′dGTP | 2.7 (2.2–4.4) | 87 (70–140) | 12 (11–13) | 0.74 (0.5–1.4) | 80 (75–85) | 32 (28–38) |
Reaction products were modeled as sums of independent contributions by fast and slow fractions of RNAP; contributions of each fraction were modeled as model (1). Upper and lower bounds were calculated at a 10% increase in Chi2 by the FitSpace routine of KinTek Explorer software.