Figure 2

Far-UV CD spectra of QueD proteins produced in vivo and in vitro. (A), Proteins purified from recombinant E. coli cells, and (B), proteins synthesized in vitro by cell-free protein synthesis in presence of 1 mM Ni²⁺, Mn²⁺, or iron salts, or 0.2 mM Cu²⁺ or Zn²⁺. Protein samples in 10 mM potassium phosphate buffer (pH 8.0) were adjusted to ~10 μM (based on measuring absorbance at 280 nm). Spectra were recorded at 25°C in a 1 mm path length cell; bandwidth: 0.1 nm (A) or 0.5 nm (B).