... titrating the protein in Hepes buffer(50 mM,pH7.4)at25°C in the presence of the f ollowingmediators (each at 43 l M): 2,6-dichlorophenolindophenol,phenazine methosulfate, thionine, methylene ... (1977) Inhibition of methylene blueformation d uring determination of the acid-labile sulfide of ir on-sulfur protein sampl es containing dithionite. Ana l. Biochem. 79,157–165.26. Dutton, P .L. ... can indeed be isolated andpurified as intact and catalytically active proteins, and(b) that the FeFe protein definitely does not contain a niron–molybdenum cofactor (FeMoco), but a clearly well-functioning...