FIGURE 7.

pH-dependence of α-ADP-ribosyl-arginine hydrolysis by ARH1. A, 25 μm α-ADP-ribosyl-[¹⁴C]arginine was incubated in 50 mm potassium phosphate buffer (pH 7.0), 10 mm MgCl₂, and 5 mm DTT for 1 h at 30 °C with (dashed lines) or without (solid lines) recombinant human ARH1 (3 pmol) before RP-HPLC separation of substrate and products. Substrate and products were detected by absorbance at 254 nm. B, α-ADP-ribosyl-[¹⁴C]arginine was incubated as in Fig. 6A, with ARH1 (3 pmol) for the indicated time at 30 °C before quantification of ADPr. Results were similar in three experiments.