Table 1.
Ligand binding to 30Sa
| Added ligand | IF3 | fMet-tRNA | mRNA | k1, μM−1s−1 | k−1, s−1 | k2, s−1 | k−2, s−1 | Kov, nM | |
|---|---|---|---|---|---|---|---|---|---|
| 1 | IF2c.GTP | + | + | AUG | 285±12 | 1.2±0.1 | 1±0.1 | 0.5±0.1 | 2.1 |
| 2 | IF2c.GTP | − | + | AUG | 310±23 | 1.2±0.24 | 0.5±0.1 | 0.75±0.10 | 5.8 |
| 3 | IF2c.GTP | + | − | AUG | 190±12 | 3.4±0.4 | 0.4±0.1 | 0.8±0.1 | 35 |
| 4 | IF2c.GTP | − | − | AUG | 111±12 | 37±5 | 1.1±0.1 | 0.9±0.1 | 273 |
| 5 | IF2c.GTP | + | + | AUU | 94±3 | 0.3±0.04 | 0.7±0.1 | 0.6±0.1 | 2.7 |
| 6 | IF2c.GTP | − | + | AUU | 79±3 | 0.1±0.03 | 0.4±0.1 | 0.6±0.12 | 1.9 |
| 7 | fMET | + | + | AUG | 14.5b | 0.45 | |||
| 8 | fMET | + | + | AUU | 15.8b | 0.43 |
a
All solutions contained IF1, mRNA, and 30S subunits in a molar ratio of 1.5:3:1. When present the ratio of IF3:30S was 1.5:1. GTP was 100 μM. For experiments 1 − 6, 30S concentration varied from 0.05 − 0.30 μM, IF2 was 0.15 μM. For experiments 7 and 8, concentrations were: 30S, 0.3 μM; IF2, 0.45 μM, fMet(Prf20) 0.18 μM. All concentrations are final.
b
in s−1