关键词: 辅酶Q₀, 电子相互作用, 方波伏安法, 多电子转移, 分峰, 单电子响应辨析

Abstract: A widely held concept in electrochemistry is that truly elementary electron-transfer reactions always involve the exchange of one electron, therefore, an overall process involving a change of n electrons must involve n distinct electron-transfer steps. It is highly desirable to resolve multiple-step electron transfer reactions into each electron transfer step. The electrochemical behaviors of coenzyme Q₀ and methylene-bridged Bis-coenzyme Q₀ were investigated by cyclic voltammetry and square wave voltammetry in nonaqueous dichloromethane containing 0.15 mol·L^-1 Bu₄NClO₄ as the supporting electrolyte. The redox reaction of coenzyme Q₀ is well described as two chemically reversible one-electron reduction processes. Bis-coenzyme Q₀ exhibits three redox waves in voltammetric experiment, as two bridged coenzyme Q₀ units show strong intramolecular electron communication. Experimental data were curve fitted with a Gaussian and Lorentzian mixed product function after subtracting the Shirley background. Results show that four-electron reduction of Bis-coenzyme Q₀ is preceded by stepwise pathways, defining as four successive, mono-electronic electron-transfer steps.

Key words: coenzyme Q₀, electron communication, square-wave voltammetry, multi-electron transfer, mono-electronic discrimination