Table 1.
Kinetic parameters of selected kinases
| Enzyme (short name) directiona | Substrateb fixed co-substrate concentrationc (activator concentration)d | |||
|---|---|---|---|---|
| Xylulokinase (XK) |
GTP Xylulose, 2.5 mM |
ATP Xylulose, 2.5 mM |
Xylulose GTP, 10 mM |
Xylulose ATP, 25 mM |
| forward | kcat = 6540 ± 177 | kcat = 6653 ± 281 | kcat = 8788 ± 375 | kcat = 7489 ± 147 |
| Km = 0.12 ± 0.02 | Km = 1.18 ± 0.18 | Km = 0.30 ± 0.07 | Km = 0.50 ± 0.05 | |
| Phosphoglycerate kinase (PGK) | GDP-e | ADP- | ||
| forward | kcat = 771 ± 20 | kcat = 733 ± 12 | ||
| Km = 0.135 ± 0.008 | Km = 0.08 ± 0.002 | |||
| nH = 1.63 ± 0.11 | nH = 4.03 ± 0.4 | |||
|
GTP 3-PG, 25 mM |
ATP 3-PG, 4 mM |
3-PG GTP, 25 mM |
3-PG ATP, 10 mM |
|
| reverse | kcat = 2831 ± 348 | kcat = 4256 ± 148 | kcat = 3273 ± 365 | kcat = 5767 ± 194 |
| Km = 4.66 ± 1.24 | Km = 0.48 ± 0.07 | Km = 6.90 ± 1.44 | Km = 0.65 ± 0.08 | |
| Pyruvate kinase (PK) |
GDP PEP, 10 mM (FBP, 0) |
ADP PEP, 10 mM (FBP, 0) |
PEP GDP, 5 mM (FBP, 0) |
PEP ADP, 5 mM (FBP, 0) |
| forward | kcat = 977 ± 48 | kcat = 9508 ± 328 | kcat = 3084 ± 312 | kcat = 9212 ± 50 |
| Km = 0.90 ± 0.14 | Km = 1.87 ± 0.14 | Km = 23.0 ± 4.0 | Km = 1.56 ± 0.02 | |
| nH = 1.41 ± 0.09f | nH = 1.32 ± 0.02 | |||
|
GDP PEP, 10 mM (FBP, 0.5 mM) |
ADP PEP, 10 mM (FBP, 0.5 mM) |
PEP GDP, 5 mM (FBP, 0.5 mM) |
PEP ADP, 5 mM (FBP, 0.5 mM) |
|
| forward | kcat = 2341 ± 102 | kcat = 9213 ± 245 | kcat = 3794 ± 218 | kcat = 9814 ± 152 |
| Km = 0.92 ± 0.09 | Km = 1.74 ± 0.11 | Km = 6.40 ± 0.81 | Km = 1.64 ± 0.07 | |
| nH = 1.40 ± 0.18 | nH = 1.39 ± 0.07 | nH = 1.24 ± 0.01 | nH = 1.26 ± 0.05 | |
|
GDP PEP, 10 mM (FBP, 3 mM) |
ADP PEP, 10 mM (FBP, 3 mM) |
PEP GDP, 5 mM (FBP, 3 mM) |
PEP ADP, 5 mM (FBP, 3 mM) |
|
| forward | kcat = 5747 ± 218 | kcat = 9032 ± 328 | kcat = 6545 ± 146 | kcat = 9585 ± 143 |
| Km = 1.06 ± 0.1 | Km = 1.75 ± 0.14 | Km = 2.75 ± 0.16 | Km = 1.52 ± 0.06 | |
| nH = 1.34 ± 0.13 | nH = 1.47 ± 0.11 | nH = 1.28 ± 0.06 | nH = 1.40 ± 0.06 | |
|
GDP PEP, 10 mM (FBP, 10 mM) |
ADP PEP, 10 mM (FBP, 10 mM) |
PEP GDP, 5 mM (FBP, 10 mM) |
PEP ADP, 5 mM (FBP, 10 mM) |
|
| forward | kcat = 7479 ± 287 | kcat = 8846 ± 383 | kcat = 7747 ± 152 | kcat = 9335 ± 90 |
| Km = 0.89 ± 0.07 | Km = 1.47 ± 0.14 | Km = 2.30 ± 0.12 | Km = 1.60 ± 0.04 | |
| nH = 1.42 ± 0.17 | nH = 1.57 ± 0.17 | nH = 1.50 ± 0.07 | nH = 1.34 ± 0.04 | |
| Acetate kinase (AK) |
GDP Acetyl-P, 5 mM |
ADP Acetyl-P, 5 mM |
Acetyl-P GDP, 10 mM |
Acetyl-P ADP, 10 mM |
| forward | kcat = 35,365 ± 1,150 | kcat = 25,437 ± 1668 | kcat = 32,137 ± 823 | kcat = 25,112 ± 1755 |
| Km = 1.47 ± 0.13 | Km = 1.13 ± 0.21 | Km = 1.28 ± 0.07 | Km = 1.49 ± 0.2 | |
|
GTP Acetate, 10 mM |
ATP Acetate, 10 mM |
Acetate GTP, 10 mM |
Acetate ATP, 10 mM |
|
| reverse | NAg | kcat = 16.68 ± 0.74 | kcat = 12.85 ± 0.85 | |
| Km = 1.47 ± 0.17 | NA | Km = 2.37 ± 0.38 | ||
aDesignates the forward or reverse reaction related to the “glycolysis direction”.
bkcat values are given in iu/µmol. Km values are in mM. The data show the means and standard deviations of three replicates.
cThe kinetics were performed at a fixed, saturating concentration of the co-substrate.
dFor the pyruvate kinase, the kinetics were performed in presence of the allosteric activator FBP at 0, 0.5, 3, and 10 mM.
eFor the phosphoglycerate kinase (forward direction), coupled assays using glyceraldehyde 3-P (at a fixed concentration) and GAPDH were performed. Therefore, the concentration of the real (co-) substrate of the enzyme (1,3-BPG) is not known.
fDesignates the Hill coefficient, when cooperativity is observed. Values of nH between 0.9 and 1.1 (no significant cooperativity) are not reported.
gNo activity detected.