Abstract
Lignocellulosic biomass represents a major renewable feedstock for sustainable produc-tion of fuels, chemicals, and materials, but its structural recalcitrance and chemical heter-ogeneity demand complementary oxidative strategies for efficient deconstruction and up-grading. Glucose–methanol–choline (GMC) oxidoreductases provide a particularly versa-tile enzymatic platform because they combine a conserved FAD-dependent catalytic framework with broad substrate scope and biological function. This review examines the major GMC oxidoreductase families relevant to biomass biodegradation and valorization, integrating structural and mechanistic features, physiological roles, and emerging bio-technological applications. These oxidoreductases act in a concerted manner to produce H2O2 and other reduced compounds that trigger either the activity of lignin- and carbohy-drate-oxidizing enzymes or Fenton reactions that degrade lignocellulose. Consequently, these enzymes enable the oxidative upgrading of biomass-derived carbohydrates, alco-hols, aromatics, and furans, while providing H₂O₂ or reducing equivalents that support complementary oxidative enzymes and multienzyme cascades. Recent structural and protein-engineering studies further demonstrate that substrate-access architecture, ac-tive-site configuration, flavin reactivity, oligomerization, interdomain electron transfer, stability, and heterologous production can be independently or coordinately optimized. Future progress will depend on translating this molecular understanding into pro-cess-oriented engineering strategies that integrate GMC oxidoreductases into robust en-zymatic networks for selective biomass deconstruction and conversion into value-added products.