Fig 6.

PPK2 as a processive enzyme. The assay mixture (10 μl) contained 50 mM Hepes-KOH (pH 8.0), 80 mM (NH₄)₂SO₄, 4 mM MgCl₂, 1 mM GDP, 100 μM [³²P]poly P (88 cpm/pmol), and 11 ng of PPK2 (Fraction 6). After incubation of the mixture at 37°C, the products were separated by PAGE using 20% acrylamide gel containing 7 M urea (34) and visualized by PhosphorImager (Molecular Dynamics). [³²P]ATP, [³²P]GTP, and [³²P]inorganic phosphate were used as standards.