Fig 4.

K_m and V_max values with poly P of various chain lengths. The assay mixture contained 50 mM Hepes-KOH (pH 8.0), 80 mM (NH₄)₂SO₄, 10 mM MgCl₂, 1 mM [8-³H]GDP (20 cpm/pmol), various concentrations of poly P, and various amounts of PPK2 (Fraction 6 in Table 1). Poly P chain lengths were poly P₁₈ (18 ± 2), poly P₂₃ (23 ± 3), poly P₂₈ (28 ± 5), poly P₃₃ (33 ± 6), poly P₄₅ (45 ± 8), and poly P₇₅₀ (as described in ref. 13). For more details, see Fig. 5 legend. In each case, the K_m and V_max were determined by a Lineweaver–Burk plot (data not shown). (A) K_m values for poly P: squares for molar concentration, diamonds for Pi residue concentration. (B) V_max values with various chain lengths.