FIGURE 5.

GTPase activity of Δ101. A, HPLC chromatograms showing the elution profile of 500 μm GTP after an overnight incubation at 37 °C in the absence (bottom) or presence of 20 or 40 μm Δ101 (top). GTP and GDP elutes at 13 and 8 min, respectively. B, counts/min versus time of a reaction containing 5 μm Δ101, 2 μCi of [γ-³²P]GTP, and increasing concentrations of GTP (10 μm (▪), 25 μm (□), 50 μm (▴), 100 μm (▾), 200 μm (•), 400 μm (○), and 800 μm (▸)) in buffer B supplemented with 200 mm KCl and 5 mm MgCl₂ at 37 °C. Linear regression of the counts/min was mathematically converted into pmol of GTP hydrolyzed/min/μmol of protein. The Lineweaver-Burk reciprocal plot (inset) leads to the K_m and V_max for the protein.