Decoding the features of important biochemical multistep electron-transfer pathways through the signatures of two-step double-regenerative electrochemical mechanism in square-wave voltammetry

Results from theoretical analyses of a two-step double-regenerative electrochemical mechanism (schematically designated as EC’EC” mechanism), examined for the first time under conditions of square-wave voltammetry, are presented. The primary emphasis is on the relevance of this complex mechanism for getting a more comprehensive understanding of analogous mechanistic pathways that frequently operate under physiological conditions. Such complex mechanistic schemes are typical of many biologically important pathways in which coupled electron-transfer steps are linked to homogeneous regenerative reactions mediated by catalytic substrates, enzymes, stable radical species, or some redox cofactors. Through systematic analysis of the forward and backward square-wave current components, the role of regenerative loops associated with both electron-transfer steps in affecting the voltammetric response and generating distinct electrochemical–catalytic signatures is elucidated. The proposed framework encompasses for the first time the interplay between electron-transfer kinetics, chemical regeneration rates, and mass transport within the time scale imposed by square-wave excitation signal. The results establish a useful framework for a unified mechanistic interpretation of complex bioelectrochemical systems, while offering a robust theoretical basis for kinetic analyses of multistep redox pathways relevant to metabolic processes, enzymatic catalysis, and redox signaling in living organisms.