FIG. 2.

RNA stimulation of ATP hydrolysis catalyzed by Hel-1a, Hel-1b, or Hel-2a. Steady-state rates of ATP hydrolysis catalyzed by Hel-1a (squares), Hel-1b (triangles), or Hel-2a (circles) were measured in the presence of nine different concentrations of poly(U). The experiments were repeated with three different amounts of enzyme, and average turnover rates (moles of ATP hydrolyzed/moles of enzyme/second) were plotted. The data were fit to equation 2, and the curves were drawn by using the resulting constants (Table 2).