Analysis of Redox Activity of Proteins on the Carbon Screen Printed Electrodes

Direct redox activity of different proteins was investigated on the surface of carbon screen printed electrodes (SPE). The signal attributed to the electrochemical oxidation of amino acid residues (cysteine (Cys), tryptophan (Trp) and tyrosine (Tyr)) was registered at E-max from 0.6 to 0.7V (vs. Ag/AgCl). Based on the difference in the redox behavior of L-tyrosine and 3-nitro-L-tyrosine, the selective electrochemical detection of native and nitrated albumins was demonstrated. It was shown that the electrochemical signal correlated with the surface density of electroactive amino acid residues on the protein molecule. A simple electrochemical method for the total protein analysis was proposed.