TABLE 1.
Kinetic parameters of recombinant SfcA and MaeB
Parameter | Valuea
|
|
---|---|---|
SfcA | MaeB | |
Malate oxidative decarboxylation (pH 7.5) | ||
kcat,NAD (s−1) | 82.7 ± 5.1 | ND |
Km,NAD (μM) | 68.8 ± 3.2 | ND |
kcat,NAD/Km,NAD | 1.2 | |
kcat,NADP (s−1) | 12.4 ± 0.6 | 66.6 ± 2.5 |
Km,NADP (μM) | 1,000 ± 78b | 41.5 ± 1.5 |
kcat,NADP/Km,NADP | 0.012 | 1.6 |
Km,malate (mM) | 0.66 ± 0.04 | 3.41 ± 0.25b |
Km,Mg (mM) | 2.03 ± 0.1 | 0.19 ± 0.01 |
Pyruvate reductive carboxylation (pH 7.0) | ||
kcat (s−1) | 2.93 ± 0.15 | 0.38 ± 0.02 |
Km,pyruvate (mM) | 2.59 ± 0.1 | 6.21 ± 0.4 |
kcat,forward/kcat,reverse | 28.2 | 175.2 |
Kinetic values are given as averages ± standard deviations. Each value was averaged over at least two different enzyme preparations. ND, no activity was detected.
Kinetics for these reactions are sigmoidal, and the reported values are K0.5 values, not true Km values. The calculated Hill coefficients were as follows: 1.95 for K0.5,NADP of SfcA and 1.42 for K0.5,malate of MaeB.