魔芋多糖固定化肌红蛋白的直接电化学与电催化

用魔芋多糖(KGM)和N,N-二甲基甲酰胺(DMF)的加合物,将肌红蛋白(Mb)固定在玻碳电极(GCE)上,制备了稳定的Mb-KGM-DMF/GCE修饰电极,并研究了Mb在修饰电极上的直接电化学行为和电催化性能。该电极在pH=7.0的磷酸盐缓冲溶液(PBS)中,-0.38 V(E0′)处有一对氧化还原峰,峰电位差ΔEp=70 mV,该峰正是Mb中血红素辅基FeⅢ/FeⅡ电对的氧化还原特征峰。在0.2~9.0 V/s扫速的范围内,氧化还原峰峰电流大小和扫描速率成正比,呈现出表面控制行为。在pH为5.0~12.0的范围内,式电位和pH值呈线性关系,表明电子传递过程伴随着质子转移。同时,Mb-KGM-DMF/GCE修饰电极表现出良好的电催化性能,对氧、H2O2有显著的催化作用。在4.70~75.0μmol/L的范围内,其催化峰电流大小与H2O2的浓度有良好的线性关系,其线性回归方程i=0.127 0.093C,r=0.9989,表观米氏常数为80.8μmol/L。

Direct Electrochemistry and Electrocatalysis of Myoglobin Entrapped in Konjac Glucomannan Films

Myoglobin (Mb) was immobilized on a glass carbon electrode (GCE) by Konjac Glucomannan (KGM) and N, N-dimethylformamide (DMF) conjugate to fabricate myoglobin modified electrode (Mb-KGM-DMF/GCE). The direct electrochemistry and electrocatalysis of myoglobin on this modified electrode have been investigated. A pair of redox peaks with formal potential of –0.38 V and Δ E_p of 70 mV were obtained on the modified electrode in PBS (pH 7.0), which resulted from the Fe^III/Fe^II couple of heme-protein. The linear dependence of peak current on scan rate in range of 0.2–9.0 V s^–1 showed a typical surface-controlled electrochemical process. The Bohr effect of redox, a shift in the formal potential as a function of pH value from 5.0 to 12.0, indicated that Mb underwent a proton-coupled electron transfer process. Moreover, the obvious catalytic reduction of oxygen in solution and hydrogen peroxide by Mb was realized on Mb-KGM-DMF/GCE. The catalytic current increased linearly with the concentration of H₂O₂ in the range of 4.70–75.0 μ M. And the apparent Michaelis-Menten constant K_m was calculated to be 80.8 μM.