| | Molecule Name/
Site Name | Km (uM) | kcat (1/s) | Ratio
(k2/k3) | Enzyme Type | Substrate | Product |
| 1 |
Enzyme Activity:
MAPKKthr
Enzyme Molecule:
MAPKK* | 0.0462963 | 0.15 | 4 | explicit E-S complex | MAPK-tyr
| MAPK*
|
| | Rate consts same as for MAPKKtyr. |
| 2 |
Enzyme Activity:
MAPKKtyr
Enzyme Molecule:
MAPKK* | 0.0462963 | 0.15 | 4 | explicit E-S complex | MAPK
| MAPK-tyr
|
| | The actual MAPKK is 2 forms from Seger et al JBC 267:20 14373(1992) Vmax = 150nmol/min/mg From Haystead et al FEBS 306(1):17-22 we get Km=46.6nM for at least one of the phosphs. Putting these together: k3=0.15/sec, ratio of 4 to get k2=0.6. k1=0.75/46.6nM=2.7e-5 In terms of Michaelis-Menten rates, Km = 0.046, Vmax = 0.15, ratio = 4. |
| 3 |
Enzyme Activity:
Raf-GTP-Ras*.1
Enzyme Molecule:
Raf-GTP-Ras* | 0.159091 | 0.105 | 4 | explicit E-S complex | MAPKK
| MAPKK-ser
|
| | This enzyme activity refers to the complex of phosphorylated Raf and activated Ras. Starting point for kinetics are the same as for the craf-1* activity, ie., k1=1.1e-6, k2=.42, k3 =0.105 These are based on Force et al PNAS USA 91 1270-1274 1994 who report a Km of 0.8 uM and Vmax of ~500 fm/min/ug for MAPKK. These parms cannot reach the observed 4X stim of MAPK. So we increase the affinity, ie, raise k1 5X to 5.5e-6 which is equivalent to a 5x reduction in Km to about 0.16. |
| 4 |
Enzyme Activity:
Raf-GTP-Ras*.2
Enzyme Molecule:
Raf-GTP-Ras* | 0.159091 | 0.105 | 4 | explicit E-S complex | MAPKK-ser
| MAPKK*
|
| | Same kinetics as other c-raf activated forms. See Force et al PNAS 91 1270-1274 1994. |
