Oxidation of Cysteine, Cysteinesulfinic Acid and Cysteic Acid on a Polycrystalline Gold Electrode.

摘要

The mechanism of cysteine, cysteinesulfinic acid and cysteic acid electrooxidation in perchloric acid solutions has been studied using cyclic voltammetry. All compounds investigated have been found to be chemisorbed on a polycrystalline gold electrode and oxidized with four, two or one electron, respectively. The water molecule co-adsorbed with cysteine participates in the latter's one-electron oxidation with a lower energy requirement whereas at the completely covered electrode surface, bulk water is involved in multiple electron transfer reactions. A strong inhibiting effect of chloride anions on cysteine oxidation has been observed at the partially covered electrode surface. The effect of adsorbate surface coverage on the reaction mechanism in anodically catalyzed reactions involving oxygen transfer is discussed.