GTPase activity of RbgA in presence of Na+ and K+ ions
The intrinsic activity of RbgA was assayed by incubation of 2 μm RbgA with 200 μm GTP for 15 min at 37 °C in the presence of 250 mm NaCl or KCl. Stimulation of GTPase activity by the ribosome was tested by incubation of 100 nm free 50 S subunits with 100 nm RbgA and 200 μm GTP for 15 min at 37 °C in the presence of 250 mm NaCl or KCl. The activity was determined by standard malachite green assay as described under “Experimental Procedures.” S.D. values for three biological replicates are presented.