Figure 5.

Demonstration that the PFV response of taTrxR is not due to flavin desorbed from the protein. (A) Addition of exogenous FAD to a taTrxR protein film. Buildup of the voltammetric response of the FAD/FADH₂ couple is observed by starting with a taTrxR-bound electrode (light solid line) and adding FAD to the electrochemical cell at final concentrations of 2, 4, and 10 μM (dotted, dashed, and heavy solid line). The buildup of the free FAD species is observable at ∼−220 mV. Other experimental features: pH 7.0, 10 °C, v = 150 mV/s. (B) Free FAD (●) and taTrxR (open square) midpoint potentials as a function of pH.