Figure 3

Activation of E. coli cytochrome bo₃ by CL. (A) Enzymatic function of cytochrome bo₃ (PDB ID: 1FFT³⁹, figure created with BioRender⁵²) (B) The effect of CL (final conc. 10 μM) on oxygen consumption activity by cytochrome bo₃ purified from E. coli (final conc. 5 nM) was determined using a Clark-type electrode. The reaction was initiated by addition of ubiquinone-1 + DTT (arrow), the negative control contained ubiquinone-1 and DTT, but no cytochrome bo₃. Inset: dependency of activation on the CL concentration. (C) Impact of KCN (2 mM) on oxygen consumption by cytochrome bo₃ in the presence or absence of 10 µM CL. (D) Effect of CL on the K_M value of purified E. coli cytochrome bo₃. Curve fit was done with a simple Michaelis–Menten analysis, R² values in the absence and presence of CL were 0.974 and 0.983, respectively. All experiments were carried out at 37 °C. Average values were calculated from at least two biological replicates; error bars represent standard deviations.