Figure 3. A: Substrate concentration dependence of rate.

The lines show the least squares fit of Eq. (1) to the data. B: Double reciprocal plots of the arsenic methylation rate against the concentration of iAs³⁺. Reaction mixtures (100 µl) containing 11 µg enzymes, 1 mM SAM and 7 mM GSH in PBS (25 mM, pH 7.0) were incubated with different concentrations of iAs³⁺ at 37°C for 2 h with H₂O₂ treatment before analysis. Values are the averages ± S.D. of three independent experiments performed by three independently purified proteins.