Table 3.
Kinetic parameters of Msh2-msh3942A ATP hydrolysis in the presence of homoduplex, MMR and 3′ NHTR DNA substrates
| 1:1 ratio | No DNA | Homoduplex DNA | + 8 loop substrate | Splayed Y substrate |
|---|---|---|---|---|
| Vmax (nM/min) a | 498 ± 58 | 450 ± 30 | 750 ± 50 | 730 ± 40 |
| Km (μM) b | 522 ± 44 | 42.1 ± 12.4 | 12.8 ± 2.0 | 8.3 ± 3.5 |
| kcat (min−1) c | 10.0 | 9 | 15 | 14.6 |
| kcat/Km (min−1μM−1) | 0.02 | 0.21 | 1.2 | 1.8 |
| Relative to no DNA d | 1 | 10.5 | 60 | 90 |
| Hill co-efficient e | 0.9 ± 0.1 | 0.8 ± 0.09 | 1.1 ± 0.1 | 0.6 ± 0.2 |
|
| ||||
| 1:5 ratio | ||||
| Vmax (nM/min) a | 498 ± 58 | 320 ± 30 | 560 ± 60 | 390 ± 38 |
| Km (μM) b | 522 ± 44 | 10.2 ± 3.1 | 11.3 ± 3.1 | 14.3 ± 5.4 |
| kcat (min−1) c | 10.0 | 6.4 | 11.2 | 7.8 |
| kcat/Km (min−1μM−1) | 0.02 | 0.6 | 1.0 | 0.5 |
| Relative to no DNA d | 1 | 30 | 50 | 25 |
| Hill co-efficient e | 0.9 ± 0.1 | 0.82 ± 0.07 | 1.0 ± 0.2 | 0.9 ± 0.1 |
a
Maximum rate of ATP hydrolysis when data fit to Michaelis-Menten or Hill equation
b
Dissociation constant determined as the concentration of ATP at half maximal ATP hydrolysis rate data fit to Michaelis-Menten or Hill equation
c
Ratio of Vmax and concentration of protein
d
kcat/Km of Msh2-msh3Y942A in the presence of DNA substrate relative to the absence of DNA
e
Determined when data fit to Hill equation