Membrane-assembly of carbon microelectrodes for the electrochemical study of redox proteins

A novel membrane-assembly of microelectrodes has been used to study the electrochemistry of several redox proteins (c-type cytochromes, ferredoxins). The solutions of protein (5 μL) were entrapped between a dialysis membrane and the assembly surface. Near-steady-state current-voltage curves were obtained; by combining cyclic and square-wave voltammetry, a detection limit of about 20 pmol of analyte was attained. In addition, it has been demonstrated that direct electron-transfer was observed for cytochrome c and ferredoxins in the presence of a promoter within the electrochemical cell. Low molar-mass agents were able to diffuse through the membrane to develop their promoting effect.