Table 1.
Estimates of dissociation constants for the oligomerization of Rep68* at various concentrations and in the presence of 1 mM ATP or ADPc
| Protein and concna (μM) |
Kd (μM) |
|||
|---|---|---|---|---|
| K2→1 | K4→2 | K8→4 | K16→8 | |
| Apo-Rep68* | ||||
| 1.0 | NDb | ND | ND | ND |
| 2.1 | 1.5 | 1.79 | 0.16 | ND |
| 4.8 | 3.26 | 1.71 | 0.15 | ND |
| 9.3 | 2.35 | 1.98 | 0.17 | 1.6 |
| 18.2 | 1.56 | 2.56 | 0.38 | 0.48 |
| Avg | 2.2 | 2.0 | 0.21 | 1.0 |
| Apo-Rep68* with ATP | ||||
| 0.7 | 4.9 | NDb | ND | ND |
| 1.8 | 2.0 | 0.43 | 0.04 | 0.16 |
| 4.2 | 0.75 | 0.9 | 0.13 | ND |
| 8.6 | 0.87 | 1.26 | 0.09 | 0.31 |
| 17 | 0.96 | 1.1 | 0.06 | 0.07 |
| Avg | 1.9 | 0.9 | 0.08 | 0.18 |
| Apo-Rep68* with ADP | ||||
| 0.9 | 0.9 | 1.1 | 0.02 | ND |
| 2.1 | 1.3 | 0.5 | 0.04 | 0.5 |
| 4.2 | 0.7 | 0.6 | 0.05 | 0.4 |
| 8.8 | 0.9 | ND | ND | 0.7 |
| 18.1 | 1.9 | 1.0 | 0.05 | 0.5 |
| Avg | 1.1 | 0.8 | 0.04 | 0.5 |
a
Total concentration of the Rep68* monomers in the cell obtained from the integration of the complete c(S) distribution from the interference data.
b
ND, not determined.
c
The ∼0.1-fold change in K8→4 relative to that for K4→2 might indicate a entropic effect caused by ring closure. Note also that there seems to be a general small decrease in the values of the dissociation constants when either ATP or ADP is added; although the effect is not large, the trend seems to be there.