Nonconventional regeneration methods for oxygenases

Abstract

In biocatalysis we use enzymes to accelerate chemical reactions. The advantage of enzymes over other chemical catalysts is their excellent performance in respect to reactivity, regioselectivity and enantioselectivity. The gentle environment at which they can optimally function further enhances their applicability to provide more sustainable alternatives for our chemical processes. The amount of different enzymes available to us is increasing, as is the variety of reactions we can catalyse with them. Enzymes are divided in 7 classes, depending on the reactions they catalyse. The first class of enzymes, the one this thesis is focussing on, is the oxidoreductase family. As the name implies, these enzymes catalyse redox reactions, the specific transfer of electrons from or to a certain reactant. To close this redox-balance, these enzymes naturally rely on coenzymes, organic structures which are needed in a stoichiometric amount. As stoichiometric addition of these compounds would greatly strain the aspired reactions, both economically as ecologically, these coenzymes are conventionally regenerated using a second enzyme system and co-substrate. Though this practice is established, it does further complicate the reaction schemes and adds waste streams to the reaction. We therefore aim a replacing these systems with new alternatives. Within the enzyme class of oxidoreductases, this thesis focuses on the subclass of oxidases and oxygenases, which all rely on oxygen in their reaction mechanisms. These enzymes are i.a. able to catalyse the regio- and enantioselective insertion of heteroatoms into molecular structures, even on inactivated bonds. These are reactions which are challenging, if not impossible, to perform using “classical” chemical methods.