Electrochemical Studies of L-Histidine

摘要

The electrochemical investigation of L-histidine in aqueous phosphate buffers at pH 7.4 and 11 has shown that L-histidine oxidation at glassy carbon occurs as a chemically irreversible process, and the current response is nonlinear with concentration. The oxidation potentials are more positive than those observed for L-cysteine under corresponding conditions. For this reason, cyclic voltammetric behavior at gold is dominated by the oxide formation process on the gold surface. The complexation of Zn~(2+) and Cu~(2+) by L-histidine in pH 7.4 MOPS buffer has been studied by square wave voltammetric (SWV) methods by considering the peak potential shift between the metal stripping peak (E~0 estimate) and the peak potential for the ML_2 complex reduction. Attempts to observe characteristic mass peaks from MALDI experiments for the zinc and copper complexes with L-histidine and L-cysteine at ML_2 compositions yielded no definitive results.