TABLE 2.
Dissociation constants of PqsBC in complex with 2-ABA or 2-AA
KD values were deduced from fluorimetric titrations (1–10 μm PqsBC and 0–3 mm 2-AA or 2-ABA). Errors reflect standard errors of mean (S.E., n ≥3). Titrations were carried out in the absence (−) or presence (+Oct-CoA) of a 10-fold excess of octanoyl-CoA over PqsBC. The values of the H269A and C129S proteins are possibly affected by minor residual activity (kcat (H269A) = 0.0005 s−1 and kcat (C129S), below detection limit of the spectrophotometric assay).
| Protein |
KD (2-ABA) |
KD (2-AA) |
||
|---|---|---|---|---|
| − | +Oct-CoA | − | +Oct-CoA | |
| μm | μm | |||
| PqsBC | 368 ± 19 | –a | 161 ± 8 | 5 ± 1 |
| PqsBCH269A | 198 ± 11 | 166 ± 12 | 117 ± 6 | 88 ± 5 |
| PqsBCC129A | 330 ± 30 | 312 ± 38 | 158 ± 12 | 141 ± 19 |
| PqsBCC129S | 411 ± 43 | 420 ± 45 | 170 ± 10 | 177 ± 8 |
| PqsBCV299N | NBb | –a | NBb | 89 ± 4 |
a Experiment was not possible due to turnover.
b No binding or KD values above detection limit (estimated to >1 mm).