Chronopotentiometric determination of redox states of peptides
Reduced and oxidized forms of peptides were studied by different electrochemical methods at carbon and hanging mercury drop (HMDE) electrodes. Striking differences between the reduced and oxidized peptides were obtained by constant current chronopotentiometric stripping analysis (CPSA) at HMDE. Peptides yielded electrocatalytic peak H at highly negative potentials (ca. - 1.75 V). Reduced peptides adsorbed at positively charged HMDE produced substantially higher peak H than the oxidized forms. Voltammetry reflected the peptide redox state less efficiently. Different orientation of reduced and oxidized molecules at the positively charged electrode and very fast potential changes in CPSA were probably responsible for the observed effects.