Fig. 5.

Mn²⁺ can support translation after removal of background Mg²⁺. (A) Reactions prepared with washed E. coli ribosomes, reducing the background Mg²⁺ to 1 mM, to which 7, 9, or 11 mM additional Mg²⁺, Fe²⁺, or Mn²⁺ were added, totaling 8, 10, or 12 mM divalent cation (M²⁺). (B) Reactions prepared using washed E. coli ribosomes and washed factor mix, which reduced the background Mg²⁺ to the low-micromolar level, to which 8, 10, or 12 mM additional, Mg²⁺_, Fe²⁺, or Mn²⁺ were added. The activity of the translation product (DHFR, which catalyzes the oxidation of NADPH, with a maximum absorbance at 340 nm) was used as a proxy for protein production. The error bars for triplicate experiments (n = 3) are plotted as the SEM.