Table 5. Kinetic constants and conversion maxima for extension of RNA primers with ribonucleotide monomers, as determined by MALDI-MSa.
| Nucleotide | Conc. [mM] | Template | pH | k' [h−1 M−1] | Conversionb | kcovc [h−1] | |
|---|---|---|---|---|---|---|---|
| OAt-UMP | (5u) | 22 | 12a | 8.9 | 1.1 | 18 | 0.07 |
| OAt-GMP | (5g) | 14 | 12c | 8.9 | 3.8 | 28 | 0.10 |
| OAt-CMP | (5c) | 7.2 | 12g | 8.9 | 4.6 | 29 | n.d.d |
| OAt-AMP | (5a) | 7.2 | 12u | 8.9 | 2.9 | 16 | 0.06 |
| MeIm-UMP | (6u) | 60 | 12a | 7.7 | 0.1 | 24 | n.d.d |
| MeIm-GMP | (6g) | 36 | 12c | 7.7 | 0.3 | 48 | 0.02 |
| MeIm-CMP | (6c) | 30 | 12g | 7.7 | 0.5 | 59 | (0.03)e |
| MeIm-AMP | (6a) | 60 | 12u | 7.7 | 0.1 | 29 | 0.01 |
aConditions: HEPES buffer (200 mM), NaCl (400 mM), MgCl2 (80 mM) 20°C, and pH 8.9 (OAt) or 7.7 (MeIm).
bCalculated conversion at infinite reaction time.
cDetermined from initial rates and calculated occupancy of extension site.
dNot determined because numerical value of dissociation constant unknown.
eBased on dissociation constant determined in salt-free solution (compare Table 3).