Table 1.
Kinetic constants of GluRS2 for tRNAGln glutamylation and of GatCAB for Glu-tRNAGln transamidation in the absence or in the presence of the second protein
| KM (µM) | kcat (s−1) | |
|---|---|---|
| GluRS2 | 0.87 ± 0.13 | 0.094 ± 0.004 |
| GluRS2 + GatCAB | 1.86 ± 0.19 | 0.24 ± 0.009 |
| GluRS2 + GatCAB | 0.69 ± 0.15 | 0.23 ± 0.015 |
| GatCAB | 0.42 ± 0.11 | 0.21 ± 0.011 |
| GatCAB + GluRS2 | 1.34 ± 0.38 | 0.21 ± 0.014 |
| GatCAB + GluRS2 | 0.97 ± 0.30 | 0.23 ± 0.019 |
Constants were measured using the assay for the first enzyme indicated. When present as the second enzyme, GatCAB and GluRS2 were in equimolar amounts (normal font), or in excess 330- and 440-fold, respectively (in bold). Reported KM values are for tRNAGln in all experiments except GatCAB alone and with an excess of GluRS2, in which they were for Glu-tRNAGln. Errors shown are the standard errors for non-linear curve-fitting of data obtained from at least two experiments.