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. Author manuscript; available in PMC: 2014 Aug 28.
Published in final edited form as: J Am Chem Soc. 2013 Aug 15;135(34):10.1021/ja405725f. doi: 10.1021/ja405725f

Figure 4.

Figure 4

Reduction of oxidized WT*K79H iso-1-Cytc by Co(terpy)22+ at 25 °C in 10 mM buffer and 0.1 M NaCl. (A) Effect of pH on the relative amplitudes of the fast phase due to direct ET to the native conformer (kobs,1), an intermediate phase due to gated ET to the His79-heme alkaline conformer (kobs,2) and a slow phase (kobs,3). The Co(terpy)22+ concentration is 4.28 mM at pH 5 (red data points), 4.68 mM at pH 6 (blue data points) and 5.14 mM at pH 7 (cyan data points). The solid black lines are fits to triple exponential rise to maximum equations. Reduction is monitored by the increase in absorbance at 550 nm, A550, as a function of time, when iso-1-Cytc is reduced by Co(terpy)22+. The time axis is logarithmic. (B) Fractional amplitudes of the three phases, fAmp,1, fAmp,2 and fAmp,3, for WT*K79H from pH 5 to 8. fAmp,1, fAmp,2 and fAmp,3 are also shown for the yK79H variant at pH 5 and 7.5.