TABLE 2.
Kinetic parameters of the purified enzyme for 7,8-dihydropterin and guanine
The purified enzyme for 7,8-dihydropterin and guanine exhibited Michaelis-Menten kinetics. The Km and Vmax were calculated using the Lineweaver-Burk plotting method. The turnover number, kcat, was calculated from the specific activity and the molecular mass of the enzyme (48 kDa). All values are means ± S.D. of three determinations.
| Substrate |
||
|---|---|---|
| 7,8-Dihydropterin | Guanine | |
| Vmax (nmol·min−1·μg−1) | 8.9 ± 0.2 | 23.6 ± 2.1 |
| Km (μm) | 1621.0 ± 73.4 | 75.7 ± 3.3 |
| kcat (s−1) | 16.3 ± 0.4 | 649.0 ± 58.2 |
| kcat/Km (m−1·s−1) | 1.0 × 104 ± 4.9 × 102 | 8.6 × 106 ± 4.1 × 105 |