TABLE 2.
ATPase activities of D239 mutant forms of NtrC and concentrations of MnATP or MgATP for half-maximal binding
| Protein | Pi releasea (pmol/15 min/10 μl)
|
Concn for half-maximal binding (μM)b
|
||
|---|---|---|---|---|
| Mg2+ | Mn2+ | MnATP | MgATP | |
| MBP-NtrC | 500 | 450 | 110 ± 15 (3) | 180 ± 20 (3) |
| MBP-NtrCD239N | ≤20 | ≤20 | ND | ND |
| MBP-NtrCD239C | ≤20 | ≤20 | 95 (2) | 25 (2) |
| MBP-NtrCD239A | ≤20 | ≤20 | 50 (1) | 35 (1) |
a
ATPase activity of phosphorylated MBP-NtrC fusion proteins was measured in the presence of MgATP or MnATP as described in Materials and Methods. Values were corrected for the background of Pi, which was 18 pmol/15 min/10 μl.
b
See footnote b to Table 1.