Bio-catalytic cascades and molecular oxygen-accessing amines and nitriles

The pursuit of sustainable chemical methodologies has led directly to utilization of enzymes in chemical processes due to their often-elevated chemo- and stereo-selectivity as well as mild operating conditions. This thesis explores the potential of bio-catalytic cascades utilizing molecular oxygen. Since there is enormous number of discovered enzymes, Chapter 1 serves as a comprehensive overview of enzymatic oxygen-dependent reactions that have been demonstrated to work on a preparative scale, or harbor a great potential for further exploitation. Chapter 2 describes an attempt to combine two classes of alcohol oxidases and amine dehydrogenases in a cascade process allowing a conversion of alcohols to amines, both in a batch- and a flow-based setup. Since amine dehydrogenases are attractive target for flow-chemistry, we have developed a methodology allowing co-immobilization of an amine dehydrogenase and a coenzyme recycling system in an agarose gel reactor, that was casted using a 3D-printed molds. The findings are reported in Chapter 3. Furthermore, Chapter 4 reports a serendipitous discovery of an unparalleled catalytic promiscuity of a copper-dependent alcohol oxidase allowing a one-pot transformation of alcohols to nitriles in presence of ammonium ions. Additionally, the elucidation of a crystal structure of engineered amine dehydrogenase is described in Chapter 5 and the obtained structural insights are further used to support a development of a multi-enzymatic cascade process, described in Chapter 6, that allowed the synthesis of 6-aminocaproic acid (open chain nylon-6 monomer) from cyclohexanol using two independent cofactor-recycling modules.