Midpoint potential measurement of HLMW b
with spectroelectrochemical titration. Spectroelectrochemical titration was conducted by recording the absorption spectrum of HLMWb5 (15 μM in 50 mM sodium phosphate buffer pH 7.0) at various redox potentials by the addition of sodium dithionite to the oxidized form at 25°C in the presence of various redox mediators (for detail, see main text). Least-square curve-fitting of the spectroelectrochemical titration data by using the Nernst equation assuming a single redox component. Solid circles indicate data points for the reductive phase and + for the oxidative phase. Other conditions are indicated in the main text.