Figure 5

Reduction of 2-hydroxyphenazine and re-oxidation dependent on membranes and CoM-S-S-CoB. The 100-μl reaction mixture consisted of membranes (107 μg protein), 4 μM ferredoxin, 100 μM 2-hydroxyphenazine and CdhAE (40 μg) in 50 mM MOPS (pH 6.8) under 1 atm CO. The reduction and oxidation of 2-hydroxyphenazine was followed by the absorbance at 475 nm (ε₄₇₅ = 2.5 mM^-1 cm^-1). CdhAE was added to initiate the reduction at time zero. At point A the cuvette was flushed with 100% N₂ and 2 μl of MOPS buffer (pH 6.8) was added. At points B and C, 2 μl of MOPS buffer (pH 6.8) containing CoM-S-S-CoB was added to the reaction reaching final concentrations of 240 and 480 μM.