FIG. 4.

Effect of temperature, MgCl₂ concentration, and hydrogen ion concentration. (Top) Temperature. Assays were conducted at the indicated temperatures under otherwise standard conditions. The inset shows selected data shown as an Arrhenius plot. (Middle) MgCl₂.Assays were conducted at the indicated concentrations of MgCl₂ under otherwise standard conditions. (Bottom) Hydrogen ion concentration. Assays were conducted in 50 mM sodium acetate, 50 mM glycine, 50 mM Tris, and 50 mM 2-(N-morpholino)ethanesulfonic acid at the indicated pH under otherwise standard conditions.