Fig. 5.

Difference spectra of membrane particles expressing only a single oxidase. Membranes were prepared from E. coli respiratory mutants and diluted with buffer to a final protein concentration of 8–19 mg/ml. Spectra were obtained 10 min after the addition of CORM-3 to membranes from the following strains: (A) wild type; (B) cytochrome bd-I only; (C) cytochrome bd-II only; (D) cytochrome bo′ only. Data were plotted using a scanning dual beam spectrophotometer as the difference between the spectrum of a dithionite reduced sample incubated with 100 μM CORM-3 minus the spectrum of a reduced sample. Data have been smoothed in Sigma plot graphing software with a sampling proportion of 0.1 and a polynomial degree of 9.