Table 2. Apparent rate constants (s−1)a.
| mRNA/tRNA | Variable | k mRNA c | k tRNA | k split |
|---|---|---|---|---|
| F7/Phe | 25 ± 1 | 4.3 ± 0.2 | 0.47 ± 0.04e | |
| thG/Phe | 26 ± 2 | 4.1 ± 0.3 | 0.39 ± 0.05 | |
| G7/Gly | 13.8 ± 0.8 | 2.9 ± 0.2 | 0.44 ± 0.02 | |
| SD-F7/Phe | 0.51 ± 0.04 | 0.53 ± 0.04 | 0.50 ± 0.04 | |
| F7/Phe | 2 μM IF3 | 25 ± 1 | 4.4 ± 0.3 | 0.50 ± 0.03f |
| 0.12 ± 0.02 | ||||
| 0.5 mM GDPNPb | 11 ± 1d | 4.3 ± 0.2 | No reaction | |
| 7.5 mM Mg2+ | 3.6 ± 0.1 | 0.49 ± 0.03 | 0.074 ± 0.004 | |
| 3 mM Mg2+ | n.d. | n.d. | 2.8 ± 0.1 | |
| Non-His tagged EF-G | 25 ± 1 | 4.2 ± 0.3 | 0.30 ± 0.03 |
aStandard conditions: 2 μM RRF, 3 μM His-tagged EF-G, 5 mM Mg2+, 0.5 mM GTP. Error ranges are standard deviations for 3–10 independent measurements.
bReplaces GTP.
cmRNA dissociation rates were measured with fl-F7-mRNA, fl-G7-mRNA, fl-SD-F7-mRNA or thG-mRNA.
dPartial release of mRNA.
eThere was no significant difference in measured rate constant when fl-mRNA-F7 replaced mRNA-F7 or when Phe-tRNAPhe(prf) replaced Phe-tRNAPhe.
fMajor reaction phase (amplitude 77 ± 6% of total change).