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. Author manuscript; available in PMC: 2010 Dec 29.
Published in final edited form as: Biochemistry. 2009 Dec 29;48(51):12252. doi: 10.1021/bi901498v

Figure 7. pH sensitivity of the [4Fe-4S] cluster.

Figure 7

Pseudo first order rate constants for cluster loss from native-WhiD (7 μM [4Fe-4S]) in aerobic (red circles), aerobic in the presence of methyl mycothiol (yellow circles) and anaerobic (blue circles) buffer are plotted as a function of pH. Solid black lines, derived from polynomial fits, are intended only to indicate overall trends. The buffer was 20 mM Tris HCl, 20 mM Mes, 20 mM BisTrisPropane, 100 mM NaCl 5% Glycerol (v/v), pH as indicated. At pH ≤ 5.5 or ≥ 9.0, 20 mM sodium citrate or 20 mM sodium carbonate, respectively, was added to increase buffer capacity (see Experimental procedures). Solutions contained ~234 μM dissolved O2, 2 mM GSH and 0.5 mM methyl mycothiol as required.