Baeyer−Villiger Monooxygenases: More Than Just Green Chemistry

Abstract

What is life without oxygen is a rhetorical question. On the other hand, unraveling the intricacies and understanding the various mechanisms underpinning the biological processes beg many answers. The activation of hydrocarbon C-H bonds by oxygenases exemplifies an important biological process and prerequisite to the eventual transformation of these raw materials into value-added chemicals or bioproducts. Oxygenases come in two forms: those that introduce one atom of molecular oxygen into an organic substrate, called monooxygenases (also referred to as mixed function oxygenases) and those that insert both oxygen atoms into a substrate, namely, dioxygenases. For a historical account on the discovery of oxygenases see a review by Hayaishi.(1) In monooxygenase-catalyzed reactions, the other oxygen atom undergoes reduction to water. Hence, in a biotransformation or biocatalysis setting, having water as a byproduct cannot be greener. This review focuses on the monooxygenase-catalyzed Baeyer-Villiger oxidation of linear or cyclic ketones as a green chemistry tool to address environmental sustainability, a system to study its molecular diversity and catalytic mechanism, industrial-scale bioprocess development, and a challenging model for protein engineering to evolve new biotechnological applications.Biocatalysis at large is poised to play an ever increasingly important role in meeting the needs of industrial and environmental sustainability as manufacturers and industries are striving to improve efficiency and implement cleaner processes.(2) In the context of the three pillars of sustainable development, the use of biocatalysts, as opposed to strictly harsh chemical methods, is meeting the needs of environmental care and social responsibility, although rapid economic progress requires serious financial investment.