Table 1. Numerical Analysis of Aminoacylation without Proofreadinga.
| rate constant (s–1) | correct (G3·U70) | incorrect (A3·U70) | correct (kcal/mol) | incorrect (kcal/mol) |
|---|---|---|---|---|
| k1 (μM–1 s–1) | 10 | 10 | ΔG(NR) | ΔG(NR) |
| k–1 | 30 | 30 | 0 | 0 |
| k2 | 500 | 500 | ΔG(R) | ΔG(R) |
| k–2 | 20 | 50 000 | –2.1 | +3.1 |
| k3 | 15 | 15 | ||
| kcat | 14.0 (14.4b) | 0.15 (0.14b) | ||
| KM (μM) | 1.6 | 3.0 | ||
| kcat/KM (μM–1 s–1) | 8.8 | 0.05 |
a
Rate constants for the nonspecific AlaRS–tRNA association (k1), dissociation from the nonspecific complex (k–1), the nonreactive (NR) ↔ reactive (R) conformational change (k2 and k–2), and for aminoacylation from the reactive complex (k3). The calculated relative binding free-energy values at the experimental temperature of 333 K22 are given in the two rightmost columns.
b
Pre-steady-state kinetic constants from ref (22).