Figure 2.

Redox characterization of MtoD. (A) Electronic absorbance of MtoD equilibrated at potentials between 0.4 and −0.4 V during a mediated potentiometric titration. Spectra are colored from blue to red corresponding to increasingly reduced protein. (B) Variation of absorbance at 549 nm (A₅₄₉) with solution potential (points) and best fit (line) to the Nernst equation for a one-electron transformation with a mid-point potential of +155 mV vs. SHE. Experiments performed in 20 mM HEPES pH 7, 100 mM NaCl at 21°C with a mediator range as listed in the methods.