Table 1. Kinetic parameters of fumarase and tartrate dehydratase activity of FumA and FumBa.
L-malate | fumarate | D-tartrate | ||||||||
b Km | c Vmax | d kcat/Km | Km | Vmax | kcat/Km | e Keq | Km | Vmax | kcat/Km | |
FumA | 0.7±0.1 | (7.2±0.4)·102 | (1.0±0.2)⋅106 | 0.46±0.08 | (19±1)·102 | (4.2±0.8)⋅106 | 4±1 | 0.8±0.3 | 2.3±0.3 | (3±1)⋅103 |
FumB | 0.30±0.07 | (4.9±0.3)·102 | (1.6±0.4)⋅106 | 0.32±0.04 | (14.3±0.6)·102 | (4.5±0.6)⋅106 | 2.8±0.8 | 0.8±0.1 | 9.2±0.4 | (12±2)⋅103 |
All values are corrected for Fe-S cluster content.
Km in mM.
Vmax in µmol product/minute/mg enzyme.
kcat/Km in s−1 M−1.
Keq is the equilibrium constant for the hydration of fumarate as calculated using the Haldane relationship: Keq = (kcat/KM)fumarate/(kcat/KM)L-malate.