Table 2. Kinetic parameters for iAs methylation of the mutant C85S.

	C85S	WT
a V max (pmolCH3/mg/h) ×103	9.4±0.6	21.2±1.1
a K M (µM)	1.7±0.3	3.2±0.3
a K I (mM)	0.44±0.12	0.76±0.09
b K M (µM)	1.5±0.2	3.2±0.7
b V max (pmolCH3/mg/h) ×103	8.3±0.6	19.8±1.0
c K M (µM)	80.0±7.4	47.8
Relative c K M	1.9	1.0

Values represent the average ± S.D. of three independent experiments performed using three independently purified proteins.

^a Represents the kinetic parameters of iAs³⁺ estimated from the data in Figure 4a by Eq. (1) using origin 8.0.

^b Represents the kinetic parameters of iAs³⁺ calculated from the data in Figure 4b.

^c Represents the K_M of SAM.