Figure 3

Ferredoxin-dependent reduction of membrane-bound cytochrome c. The 100-μl reaction mixture consisted of purified membranes (300 μg protein), the indicated amount of ferredoxin, 1 μg FNR and 1 mM NADPH in 50 mM MOPS (pH 6.8). The reaction was initiated by addition of FNR (Sigma). The reduction of cytochrome c was followed at 554 nm. Panel A, time-course for the reduction of cytochrome c. Symbols: (filled squares) 4 μM ferredoxin; (open circles) 0.2 μM ferredoxin; (open squares) minus ferredoxin; (open triangles) minus FNR; (filled circles) minus NADPH. Panel B, reduced minus oxidized spectra recorded at the indicated times after initiation of the reaction containing 4 μM ferredoxin.