Workpackage 2: Light-driven in vitro photobiocatalysis

The work package aims to understand and develop concepts and methods for the in vitro exploitation of light driven reactions. This encompasses:

1. investigations of the light harvesting systems including artificial as well as natural systems 
2. identification of suitable cofactors and optimization of electron transfer as well as 
3. elucidating reactions by enzymes which require light for the reaction itself.

For instance, pterins and folate derivatives will be evaluated as photoantenna cofactors concerning their properties and efficiency capturing photons. The concept will be demonstrated by coupling the light reaction to selective mono- and dihydroxylations of arenes and olefins catalyzed by Rieske non-heme iron oxygenases. Alternatively, the foundation for a photosystem 1 (PS1) based photocatalytic platform for light-driven in vitro biocatalysis with nicotinamide coenzyme reduction as model reaction will be laid out (ESR 8) in close collaboration with ESR 9 who will investigate synthetic nicotinamide coenzyme biomimetics (NCBs) for biotechnological applications. ESR 6 will develop the concept for combining an artificial water splitting photosystem with a Baeyer-Villiger monooxygenase. Protein scaffold-enzyme complexes combined to photocatalysis will be evaluated in terms of enzyme stability and activity. An example for an enzymatic reaction that requires light for the reaction itself, is catalyzed by the oxygen-insensitive but light-dependent protochlorophyllide reductases (LPORs), which perform the reduction of a C=C double bond adjacent to a pyrrole ring in nature at the expense of NADPH and light. The reaction and substrate requirements of light-driven (asymmetric) reduction of pyrrol derivatives will be elucidated (ESR 7).