TABLE 4.
Catalytic parameters of tobacco apo-Rca as a function of free magnesium ion concentration, derived from individual curve fitting procedures
Experiments were carried out at 5 μm Rca. The data sets were fit individually to Equation 1 for each ADP concentration, and the catalytic efficiency kcat/Km (app) was calculated from the fitted parameters. In all cases, the best fits were obtained with a Hill coefficient nH = 1.0. Indicated errors are estimates provided by the curve fitting algorithm. NA, not applicable.
| [Mg2+]free | kcat | Km (app) | kcat/Km (app) |
|---|---|---|---|
| mm | min−1 | mm | min−1 mm−1 |
| 0.1 | 16.4 ± 1.1 | 0.453 ± 0.110 | 36.3 ± 9.2 |
| 1.0 | 23.5 ± 0.8 | 0.323 ± 0.046 | 72.8 ± 10.6 |
| 1.5 | 27.6 ± 1.1 | 0.292 ± 0.051 | 94.4 ± 16.6 |
| 2.0 | 21.3 ± 0.8 | 0.119 ± 0.021 | 179 ± 32 |
| 3.0 | 24.1 ± 0.5 | 0.113 ± 0.014 | 214 ± 27 |
| 4.0 | 20.9 ± 0.5 | 0.079 ± 0.014 | 264 ± 47 |
| 5.0 | 22.8 ± 0.6 | 0.083 ± 0.021 | 275 ± 70 |
| 6.5 | 19.1 ± 0.6 | 0.069 ± 0.014 | 277 ± 57 |
| 8.5 | 20.7 ± 0.5 | 0.067 ± 0.011 | 309 ± 51 |
| 10.0 | 20.7 ± 0.3 | 0.068 ± 0.005 | 304 ± 23 |
| Average ± S.D. | 21.7 ± 3.0 (n = 10) | NA | NA |