Flavoenzymes: Versatile catalysts in biosynthetic pathways

Abstract

Covering: up to the end of May 2012

Riboflavin-based coenzymes, tightly bound to enzymes catalyzing substrate oxidations and reductions, enable an enormous range of chemical transformations in biosynthetic pathways. Flavoenzymes catalyze substrate oxidations involving amine and alcohol oxidations and desaturations to olefins, the latter setting up Diels–Alder cyclizations in lovastatin and solanapyrone biosyntheses. Both C_4a and N₅ of the flavin coenzymes are sites for covalent adduct formation. For example, the reactivity of dihydroflavins with molecular oxygen leads to flavin-4a-OOH adducts which then carry out a diverse range of oxygen transfers, including Baeyer–Villiger type ring expansions, olefin epoxidations, halogenations via transient HOCl generation, and an oxidative Favorskii rerrangement during enterocin assembly.