Figure 5.

The relative Cu_A content, Cu_B content and O₂ reduction activity of purified aa₃-type CcO assembled in wild-type cells grown in 1.6 µM Cu²⁺ or <50 nM Cu²⁺ (low Cu), and in cells lacking PCu_AC or PrrC and grown in <50 nM Cu²⁺. The fractional content of Cu_A, relative to wild-type cells grown in 1.6 mM Cu²⁺, is taken from the amplitudes of the g = 2.03 signal in Figure 3. The fractional content of Cu_B is estimated as described in Results. The relative activities are taken from the TN_max values for cytochrome c-driven O₂ reduction measured at pH 6.5 as described in Varanasi and Hosler [59]. The TN_max for the wild-type aa₃-type CcO grown in 1.6 mM Cu²⁺ (100%) is 1717 ± 41 e⁻ sec⁻¹.