Table 2. Kinetic parameters of arsenic methylation for the five mutants S79A, M103A, Q107A, I136A and E137A.
| aVmax(pmol CH3 /mg/h)×103 | aKM(µM) | KI(mM) | bVmax(pmol CH3 /mg/h) ×103 | BKM (µM) | CKM (µM) | Relative cKM | |
| S79A | 23.7±0.5 | 2.4±0.2 | 0.24±0.01 | 22.3±0.5 | 2.1±0.1 | 93.1±2.4 | 1.9 |
| M103A | 1.7±0.2 | 4.6±0.8 | 0.27±0.08 | 1.8±0.2 | 4.8±0.1 | 750.4±25.6 | 15.7 |
| Q107A | 4.6±0.3 | 7.0±0.8 | 0.22±0.03 | 4.1±0.4 | 6.0±0.2 | 50.2±2.0 | 1.0 |
| I136A | 3.1±0.3 | 3.7±0.5 | 0.16±0.02 | 3.0±0.3 | 3.4±0.5 | 426.7±17.9 | 8.9 |
| E137A | 13.2±1.0 | 3.0±0.5 | 0.21±0.04 | 13.5±0.8 | 3.0±0.2 | 241.9±23.5 | 5.1 |
| WT | 21.2±1.1 | 3.2±0.3 | 0.76±0.09 | 19.8±1.0 | 3.19±0.7 | 47.8 | 1.0 |
Values represent the average ± S.D. of three independent experiments performed by three independently purified proteins.
a
Represents the kinetic parameters of iAs3+ estimated from the data in Fig. 2a by Eq. (1) using origin 8.0.
b
Represents the kinetic parameters of iAs3+ calculated from the data in Fig. 2b.
c
Represents the KM for SAM.