FIGURE 6.
Cys206 is essential for Cd-MsrA to couple to the MSH/Mrx1/Mtr reduction pathway. A, in the presence of l-Met-SO and the MSH/Mrx1/Mtr pathway, Cd-MsrA shows consumption of NADPH. Doubling of the Cd-MsrA concentration resulted in doubling of the initial velocities. Cd-MsrA concentrations of 7.5, 15, and 30 μm resulted in initial velocities of 4.9, 10, and 22 milliabsorbance units/min. B, doubling of the Mrx1 concentration had no effect on the initial velocity. C, MSH/Mrx1/Mtr-coupled assay progress curves obtained using the WT and four Cys mutants of Cd-MsrA are shown. D, steady-state kinetics for the WT and C215S Cd-MsrA mutant. The plot of vi/E0 versus substrate concentration is shown. The data are presented as a mean ± S.D. (error bars) of three independent experiments.