Figure 3.

Analysis of induction period of the Mg₂PPi precipitation formation without the transcription reaction. (A) Experimentally measured time course of turbidity at various PPi concentrations from 2.50 to 0.75 mM (plots). The time points were 0, 2, 5, 8, 12, 16, 20, 24, 28, 32, 40, 48, and 64 min (2.50, 2.25, 2.00, 1.75, and 1.50 mM), 0, 10, 20, 30, 40, 50, 60, 80, 100, 120, 140, 160, and 180 min (1.25 and 1.00 mM), and 0, 20, 40, 60, 80, 100, 120, 140, 160, 180, 210, 240, and 270 min (0.75 mM). (Error bars) Standard deviation of triplicate experiments. (Lines) Fitting Eq. 6 to the mean value of the above experimental data. (B) Plot of induction period as a function of supersaturation ratio (plots) and fitting result obtained using Eq. 9 (shown as a line). The induction period was extracted from the time course data in panel A (see Materials and Methods). The supersaturation ratio was calculated by the equilibrium calculation (see Materials and Methods) and Eq. 7, where [Mg²⁺]_total = 4 mM, each [NTP⁴⁻] _total = 0 mM, [Tris] _total = 40 mM, [H⁺] _total = 25 mM, and [PPi⁴⁺] _total were the added concentrations. The induction period and the supersaturation ratio are shown in Table S1 in the Supporting Material.