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 Ep of 70 mV were obtained on the modified electrode in PBS (pH 7.0), which resulted from the FeIII/FeII 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 Km was calculated to be 80.8 μM.