Investigation of the electrochemical behavior of tryptophan by in situ circular dichroic spectroelectrochemistry

Abstract

The electrochemical redox processes of tryptophan were studied by in situ circular dichroic (CD) spectroelectrochemistry with a long optical path length thin-layer cell. The oxidation of tryptophan at low concentrations in basic aqueous solution is a two-electron irreversible electrochemical process which results from an irreversible subsequent chemical reaction. A method of treatment of CD spectral data for the irreversible electrochemical reaction is suggested, from which the values E p/2 = 0.46 V, α n α = 0.313 and k 0 = 2.4×10 −4 cm s −1 (the standard heterogeneous reaction rate constant for tryptophan oxidation) were obtained.