Lipoxygenase: Unprecedented Carbon-Centered Lignin Activation

The biotechnological conversion of lignocellulosic biomass is a pivotal aspect in the development of sustainable and environmentally friendly biorefinery and valorization processes for nonfossil biomass. Lipoxygenase, a noncellulolytic oxidizing enzyme normally operating on linoleic acid metabolism, is demonstrated to catalyze the oxidative functionalization of lignin. Lipoxygenase was used for structurally altering the most important types of technical lignins. Noteworthy oxidation is achieved by activation via a radical mechanism leading to both oxygen- and carbon-centered radicals. Since this activation also occurs on the lignin backbone, the ketyl and benzyl radicals generated can be used to functionalize lignins via formation of carbon-carbon bonds.