Competition Between Enzymatic and Anodic Oxidation in Electro-chemical Galactose Oxidase Catalysis

Electrochemical activation of galactose oxidase (GalOx) has emerged as a sustainable alternative to peroxide-driven systems for aerobic alcohol oxidation. Here, we present a systematic investigation of wild-type GalOx under electrochemical conditions for the oxidation of non-carbohydrate primary alcohols. While benzylic substrates undergo selective enzyme-mediated oxidation to the corresponding alde-hydes, we identify a prominent competing pathway in which weakly bound substrates are directly oxidized at the electrode surface, fre-quently resulting in over-oxidation to carboxylic acids. Using 4-methoxybenzyl alcohol as a diagnostic probe, we disentangle the enzymat-ic and non-enzymatic pathways and demonstrate that both applied potential and electrode material exert decisive control over product selectivity. In contrast, aryl 1,2-diols are oxidized exclusively through a direct anodic mechanism, completely bypassing enzymatic turno-ver. Collectively, these results define critical operational boundaries for electro-enzymatic GalOx catalysis and underscore the necessity of rigorous enzyme-free controls in the development of selective electrochemical biocatalytic oxidation platforms.