Figure 4.

ATPase activity and gel filtration profile of NorRΔGAF. (A) Plot of ATP turnover versus protein concentration, measured at a fixed concentration of ATP as substrate (1 mM). (B) Log of relative ATP hydrolysis rate V (compared to maximum rate Vmax at 47 μM) was plotted against the log of NorRΔGAF concentration. The slope of the linear regression slope was used to determine the Hill coefficient (1.98). (C) Different concentrations of NorRΔGAF were chromatographed at 4°C (upper) or preincubated with 1 mM ATP and chromatographed in the presence of 1 mM ATP at 4°C (lower). Corresponding molecular weight of standard globular proteins were indicated at their elution volume.