Table 2. Kinetics of Yeast PDE1 (1–369).
| cAMP |
cGMP |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| enzyme | ion in assay buffer | KM (μM) | Vmax (μmol mg–1 min–1) | kcat (s–1) | kcat/KM (s–1/μM) | KM (μM) | Vmax (μmol mg–1 min–1) | kcat (s–1) | kcat/KM (s–1/μM) | (kcat/KMcAMP)/(kcat/KMcGMP) |
| yPDE1 | 10 mM MgCl2 | 98.8 ± 8.5 | 30.1 ± 0.7 | 21.0 ± 1.0 | 0.213 | 96.8 ± 8.1 | 21.5 ± 0.5 | 15.1 ± 1.5 | 0.156 | 1.4 |
| yPDE1 | 0.01 mM ZnCl2 | 115.7 ± 7.4 | 24.8 ± 0.4 | 17.4 ± 1.1 | 0.150 | 104.8 ± 13.7 | 15.4 ± 0.5 | 10.8 ± 0.2 | 0.103 | 1.5 |
| yPDE1 | 2 mM MnCl2 | 117.5 ± 16.8 | 16.8 ± 0.6 | 11.8 ± 0.9 | 0.100 | 191.3 ± 32.3 | 20.4 ± 1.3 | 14.3 ± 2.0 | 0.075 | 1.3 |
| yPDE1 | no ion | 110.1 ± 14.2 | 24.1 ± 0.8 | 16.9 ± 1.3 | 0.153 | 104.7 ± 10.2 | 16.9 ± 0.4 | 11.8 ± 1.0 | 0.113 | 1.4 |
| yPDE1a | no ion | 81.2 ± 7.4 | 20.5 ± 0.5 | 14.3 ± 0.4 | 0.176 | 147.4 ± 20.0 | 17.2 ± 0.7 | 12.1 ± 1.6 | 0.082 | 2.1 |
| yPDE1a | no ion with 1 mM EDTA | 77.3 ± 12.0 | 15.8 ± 0.6 | 11.1 ± 1.5 | 0.144 | 153.9 ± 23.2 | 16.7 ± 0.7 | 11.7 ± 2.0 | 0.076 | 1.9 |
a
yPDE1 protein was dialyzed three times against a buffer of 50 mM Tris-HCl (pH 7.5), 50 mM NaCl, and 1 mM EDTA (1 h, 2 h, and overnight).