TABLE 1.
Analysis of SARS-CoV MBP-nsp13 NTPase substrate specificitya
| Nucleotide | Km (μM) | kcat (s−1) | kcat/Km (μM−1 s−1) |
|---|---|---|---|
| ATP | 1.23 ± 0.12 | 2.3 ± 0.2 | 1.87 |
| UTP | 3.40 ± 0.07 | 1.5 ± 0.3 | 0.44 |
| GTP | 0.82 ± 0.05 | 1.5 ± 0.2 | 1.83 |
| CTP | 1.37 ± 0.05 | 1.3 ± 0.3 | 0.95 |
| dATP | 1.14 ± 0.04 | 1.5 ± 0.1 | 1.32 |
| dTTP | 3.01 ± 0.70 | 0.6 ± 0.1 | 0.20 |
| dGTP | 0.88 ± 0.12 | 0.6 ± 0.1 | 0.68 |
| dCTP | 2.86 ± 0.45 | 0.9 ± 0.1 | 0.31 |
a
The kinetic constants for NTP hydrolysis were determined from Hofstee plots (26) by the assay described in Materials and Methods. The reactions were performed with 10 nM enzyme in the presence of NTP and dNTP concentrations ranging from 0.5 to 10 μM.