FIG. 2.
Variation of the concentration of reduced cytochromes as a function of time during the reduction of Fe(III) complexes at pH 7.0. (A) Fe(III)-citrate reaction with OmcA. The starting concentrations were as follows: Fe(III), 2 × 10−4 M; citrate, 3 × 10−4 M; and OmcA, 3.3 × 10−6 M. The inset shows the corresponding concentration dependence. (B) Reduction of Fe(III)-citrate complex at [Fe(III)]/[OmcA] ratios of 6:1 by MtrC (line a) and OmcA (line b). The starting concentrations were as follows: Fe(III), 2 × 10−4 M; citrate, 2 × 10−3 M; and MtrC or OmcA, 3.3 × 10−5 M. (C) Reduction of Fe(III) complex with citrate (line a), NTA (line b), and EDTA (line c) by reduced OmcA. The starting concentrations were as follows: Fe(III), 2 × 10−4 M; citrate, NTA, or EDTA, 2 × 10−3 M; and OmcA, 3.3 × 10−5 M.