Table 2.
Recognition of E. coli tRNALys variants by H. pylori LysRS
| Anticodon | KM tRNA (μM) | kcat (min−1) | kcat/KM (R)* |
|---|---|---|---|
| UUU | 0.94 ± 0.1 | 51 ± 2 | 1 |
| CUU | 0.81 ± 0.3 | 32 ± 3 | 1.4 |
| GUU | 0.66 ± 0.1 | 1.6 ± 0.1 | 22 |
| UCU | — | — | 9,100† |
| UGU | NA | NA | — |
| UUC | 0.82 ± 0.2 | 6.3 ± 0.7 | 7 |
| mnm5s2UUU‡ | 1.6 ± 0.2 | 117 ± 8 | 0.7 |
NA, no detectable activity.
*
Relative value expressed as fold decrease in kcat/KM compared to aminoacylation of in vivo produced E. coli tRNALys containing an unmodified anticodon.
†
Due to the high KM compared to practical tRNA concentrations ([S]≪KM), kcat/KM was directly estimated from the equation v = kcat/KM([E][S]).
‡
Fully modified, including t6 modification of A37, which is absent from the other variants investigated.