Table 1.
Comparison of kinetic constantsa of the conversion of CS2 (to H2S and COS) and COS (to H2S) by purified CS2 hydrolases from Acidithiobacillus thiooxidans strains S1p and G8 with those of Acidianus A1-3 CS2 hydrolase
| Strain | CS2 |
COS |
||||
|---|---|---|---|---|---|---|
| Km | Vmax | Kcat/Km | Km | Vmax | Kcat/Km | |
| A. thiooxidans S1p | 93 ± 21 | 32 ± 2 | 8.4 × 106 | 74 ± 11 | 34 ± 2 | 1.1 × 107 |
| A. thiooxidans G8 | 46 ± 6 | 131 ± 4 | 6.4 × 107 | 14 ± 2 | 97 ± 3 | 1.6 × 108 |
| Acidianus A1-3b | 130 ± 3 | 40 ± 0 | 7.3 × 106 | 22 ± 3 | 74 ± 3 | 8.0 × 107 |
a
Km values are expressed in μM substrate in the buffer ± standard error of the mean (SEM); Vmax is given in nmol product · min−1 · μg enzyme ± SEM. Km, Vmax, and Kcat/Km values (in S−1 · M−1) were determined by nonlinear regression using GraphPad Prism 5.04 (n ≥ 9).
b
Data from reference 21.