Figure 1.

Flavodoxin II on Basal Plane Graphite Electrodes Modified with DDAB. (A) Cyclic voltammograms in the presence (black) or absence (gray) of 200 µM native A. vinelandii flavodoxin II in 50 mM potassium phosphate, pH 7.5, 150 mM NaCl. E ₁ and E ₂ can be observed on this voltammogram at −483 ± 1 and −187 ± 9 mV, respectively. Standard errors were calculated from 3 separate cyclic voltammograms acquired with 3 different electrodes and 2 different batches of proteins. The voltammogram was acquired at a scan rate of 10 mV/s. (B) The DDAB‐modified basal plane graphite electrode was soaked for twenty minutes in a 200 μM solution of recombinant flavodoxin II purified from E. coli in 50 mM potassium phosphate, pH 7.5, 150 mM NaCl. The electrode was transferred to 10 mM phosphate buffer, pH 7, and a cyclic voltammogram was acquired at a scan rate of 50 mV/s. E ₁ and E ₂ values are −427 ± 3 mV and −151 ± 3 mV, respectively. (C) Square wave voltammogram of flavodoxin II on DDAB‐modified basal plane graphite electrodes showing the reduction potentials of E ₁ and E ₂.