Table 2. Human PFK isoforms display distinct kinetic properties.
| PFK-M | PFK-L | PFK-P | ||
|---|---|---|---|---|
| F6P | VmaxF6P (µmoles/min.mg) | 5.56 (0.18) | 3.69 (0.09) | 1.26 (0.21) |
| K0.5F6P (µM) | 147.1 (13.6) | 1360 (40) | 1333 (312) | |
| kcatF6P (s−1) | 8.11 (0.27) | 5.38 (0.14) | 1.83 (0.31) | |
| kcatF6P/K0.5F6P (s−1 µM−1) | 3.8 × 10−2 (1.32 × 10−2) | 2.71 × 10−3 (2.25 × 10−3) | 9.45 × 10−4 (6.73 × 10−4) | |
| h (F6P) | 1.82 (0.26) | 3.10 (0.22) | 2.18 (0.75) | |
| ATP | VmaxATP (µmoles/min.mg) | 38.4 (0.9) | 39.3 (1.2) | 27.2 (2.5) |
| K0.5ATP (µM) | 151.8 (10.0) | 160.1 (13.5) | 275.6 (84.4) | |
| kcatATP (s−1) | 56.0 (1.2) | 57.3 (1.7) | 39.7 (1.7) | |
| kcatATP/K0.5ATP (s−1 µM−1) | 0.37 (0.12) | 0.36 (0.13) | 0.14 (0.02) | |
| h (ATP) | 1.03 (0.05) | 1.12 (0.08) | 0.76 (0.09) | |
| GTP | VmaxGTP (µmoles/min.mg) | 17.82 (0.44) | 25.39 (0.56) | 12.30 (0.62) |
| K0.5GTP (µM) | 96.7 (8.0) | 157.8 (10.8) | 131 (20.9) | |
| kcatGTP (s−1) | 26.0 (0.6) | 37.0 (0.8) | 17.9 (0.9) | |
| kcatGTP/K0.5GTP (s−1 µM−1) | 0.27 (0.08) | 0.23 (0.07) | 0.14 (0.04) | |
| h (GTP) | 1.19 (0.12) | 1.18 (0.08) | 1.12 (0.18) |
Values are for kinetic properties determined by titrating the substrate listed in first column. For F6P titrations: ATP = 0.5 mM; n = 6. For ATP titrations: F6P = 4 mM; n = 6. For GTP titrations: F6P = 4 mM; n = 3. Values are mean averages with standard deviations in parentheses.