Table 2.
Kinetic parameters of Asp1/Vip1 pyrophosphatase activity
| Species | Construct | Substrate | Km, µM | Vmax, nmol/min/mg | kcat, s−1 | kcat/Km, 103 M−1⋅s−1 |
| S. pombe | Asp1-HAP | 1-IP7 | 17.4 | 227 | 0.24 | 13.5 |
| S. pombe | Asp1-HAP | 5-IP7 | 11.4 | 18.3 | 0.02 | 1.7 |
| S. pombe | Asp1-HAP | 1,5-IP8 | 14.0 | 123 | 0.13 | 9.1 |
| S. pombe | Asp1-FL-D333A | 1-IP7 | 15.0 | 93.2 | 0.16 | 10.9 |
| S. cerevisiae | Vip1-HAP | 1-IP7 | 5.0 | 106 | 0.12 | 23.4 |
| M. musculus | Vip2-FL | 1-IP7 | 5.9 | 51.2 | 0.11 | 18.6 |
| M. musculus | Vip2-FL | 5-IP7 | 10.8 | 7.7 | 0.017 | 1.6 |
| M. musculus | Vip2-FL | 1,5-IP8 | 6.8 | 44.2 | 0.095 | 14.0 |
Kinetic constants were determined by fitting enzyme activity determinations of at least three independent measurements by nonlinear regression to the following equation: Y = Vmax*X/(KM + X).