TABLE 1.
Kinetic parameters of steady-state αCaMKII activity stimulated by wild type and mutant CaMs
Each value represents the mean of three sets of measurements. The Vmax values represent the mean of values obtained in the different substrate dependencies, and the error given is S.D.
| Km of syntide 2 | Kact1 of Ca2+ | Hill coefficient of Ca2+ | Kact2 of Ca2+n·CaM | Km4 of ATP | Vmax (μmol of ADP) | |
|---|---|---|---|---|---|---|
| μm | μm | n | μm | μm | min−1mg−1 | |
| CaM | 12.4 ± 2.9 | 0.50 ± 0.04 | 4.4 ± 1.3 | < 0.05 ± 0.02a | 46 ± 13 | 5.1 ± 1.2 |
| CaM1 | 14.8 ± 5.5 | 1.56 ± 0.21 | 1.6 ± 0.3 | 2.9 ± 0.8 | 50 ± 17 | 1.8 ± 0.6b |
| CaM2 | 22.0 ± 6.4 | 0.75 ± 0.07 | 4.0 ± 1.8 | 0.7 ± 0.1 | 60 ± 16 | 3.8 ± 0.5 |
| CaM3 | 7.8 ± 2.7 | 1.03 ± 0.04 | 4.3 ± 0.7 | 1.2 ± 0.9 | 188 ± 37b | 2.1 ± 0.3b |
| CaM4 | 22.0 ± 7.5 | 0.65 ± 0.08 | 2.4 ± 0.7 | 1.4 ± 0.6 | 80 ± 42 | 2.3 ± 0. 5b |
| CaM12 | 23.7 ± 8.2 | 0.50 ± 0.09 | 1.8 ± 0.5 | < 0.05 ± 0.02a | 59 ± 11 | 1.9 ± 0.7b |
| CaM34 | 37.5 ± 25 | 64 ± 4b | 3.2 ± 0.6 | 87 ± 25b | 119 ± 22b | 2.2 ± 0.7b |
a Determined in the presence of 100 nm enzyme.
b Indicates significant difference from the value of the given parameter for wild type CaM. Significance was determined as described under “Materials and Methods.”