Meng Rong, Weber Stephen G
J Electroanal Chem (Lausanne). 2007 Feb 15;600(2):325-334. doi: 10.1016/j.jelechem.2006.09.024.
Thyrotropin-releasing Hormone (TRH) forms an electroactive Cu(II) complex in aqueous solution. Rotating ring-disk electrochemistry reveals oxidation at the disk electrode and reduction at the ring electrode. The plot of limiting current vs. square root of rotation frequency deviates from the Levich equation, indicating both preceding and following chemical reactions. The reaction following the oxidation is a multiple-electron ECE-type of process that has been seen before in Cu(II)-peptide electrochemistry. The preceding reaction is unusual. The deviation from diffusion-controlled behavior is more pronounced at higher initial concentration of Cu(II) and peptide. We propose that a non-electroactive dimer, Cu(II)(2)-TRH(2), is in a slow equilibrium with the electroactive Cu(II)-TRH. Simulation of the RRDE behavior of the postulated Cu(II)-TRH system has succeeded in matching experimental data. Capillary electrophoresis indicates that there is a negative charge on the dimer. It is suggested that a hydroxo-bridge may link the two Cu(II) centers. Calculations verify that bi-nuclear Cu(II)(2)-TRH(2) complexes are possible.
促甲状腺激素释放激素（TRH）在水溶液中形成一种电活性的铜（II）络合物。旋转环盘电化学显示在盘电极上发生氧化，在环电极上发生还原。极限电流与旋转频率平方根的关系图偏离了列维奇方程，表明存在前置和后续化学反应。氧化后的反应是一种多电子ECE型过程，此前在铜（II）-肽电化学中已见过。前置反应不同寻常。在较高的铜（II）和肽初始浓度下，偏离扩散控制行为更为明显。我们提出一种非电活性二聚体Cu（II）₂-TRH₂与电活性铜（II）-TRH处于缓慢平衡状态。对假定的铜（II）-TRH体系的RRDE行为进行模拟已成功匹配实验数据。毛细管电泳表明二聚体上存在负电荷。有人认为可能是一个羟基桥连接两个铜（II）中心。计算证实双核Cu（II）₂-TRH₂络合物是可能的。
