Exploiting the catalytic power of enzymes for oxy- and amino-functionalization reactions

Biocatalysis might effectively address the challenges associated with green and sustainable chemical synthesis. In the work described in this thesis, native and newly engineered enzymes were used for the step-economic and more sustainable biocatalytic synthesis of valuable precursors to pharmaceuticals and nutraceuticals, including enantioenriched epoxides, vicinal triols and amino acids. First, a non-natural aldolase and a non-natural peroxygenase, both evolved in the laboratory from the promiscuous enzyme 4-oxalocrotonate tautomerase, were combined to develop a one-pot two-step enzymatic cascade for the preparation of α,β-epoxy-aldehydes. The addition of a specifically selected natural epoxide hydrolase to the same pot yielded a short pathway to enantioenriched aryl glycerols from simple biomass-derived starting materials. Second, the laboratory evolution of the enzyme ethylenediamine-N,N'-disuccinic acid (EDDS) lyase generated an enzyme variant that showed a large improvement in activity, enabling the effective and enantioselective synthesis of complex L-aspartic acid derivatives, valuable precursors to the artificial dipeptide sweeteners neotame and advantame. These results present new opportunities to develop practical multienzymatic processes for the more sustainable and step-economic synthesis of an important class of food additives. Finally, a study into the structure, mechanism and biocatalytic potential of a newly discovered monooxygenase, named Rhop3, is presented.