TABLE 1.
Kinetic parameters of cPKA-catalyzed phos pho ryl a tion of KKSRSASTISK, Kemptide, and KKSRAASTISK peptides
Substrate concentrations used were 1, 2.5, 5, 7.5, 10, 15, 20, 25, 50, 75, 100, 150, 200, 250, 300, and 350 μm; cPKA and ATP were 2.0 μg/ml and 0.2 mm, respectively.KmandVmaxvalues were calculated by linear regression analysis of Lineweaver-Burk or Eadie-Hofstee plots or by Michaelis-Menten analysis (Fig. 8B). Values are expressed as the mean ± S.E. of three experiments performed in triplicate. − indicates no32P incorporation.
| Analysis | Peptide | Km | Vmax | Km/Vmax |
|---|---|---|---|---|
| μm | μmol Pimg−1min−1 | |||
| Michaelis-Menten | KKSRSASTISK | 133.8 ± 30.0 | 3.8 ± 0.4 | 35.2 |
| Kemptide | 39.9 ± 2.8 | 6.1 ± 0.1 | 6.5 | |
| KKSRAASTISK | − | − | − | |
| Lineweaver-Burk | KKSRSASTISK | 101.8 ± 26.7 | 2.7 ± 0.6 | 37.7 |
| Kemptide | 35.1 ± 3.6 | 5.8 ± 0.2 | 6.1 | |
| KKSRAASTISK | − | − | − | |
| Eadie-Hofstee | KKSRSASTISK | 98.7 ± 25.7 | 3.1 ± 0.09 | 38.1 |
| Kemptide | 34.9 ± 2.7 | 5.8 ± 0.1 | 6.0 | |
| KKSRAASTISK | − | − | − |