A Minimal Light‐Driven System to Study the Enzymatic CO2Reduction of Formate Dehydrogenase

Abstract

AbstractA minimal light‐driven approach was established for studying enzymatic CO2conversion spectroscopically. The system consists of a photosensitizer Eosin Y, EDTA as a sacrificial electron donor and substrate source, and formate dehydrogenase fromRhodobacter capsulatus(RcFDH) as a biocatalyst. This simplified three‐component system provides a photo‐triggered control forin situcharacterization of the entire catalytic reaction. Direct reduction ofRcFDH by the photosensitizer without additional electron carriers was confirmedviaUV‐Vis spectroscopy, while GC‐MS and IR spectroscopy were used to follow photoinduced CO2generation from EDTA and its subsequent enzymatic reduction, yielding the product formate. Photo‐driven andin vitro, dye‐based CO2reduction was inhibited by azide under a mixed (competitive‐non‐competitive) inhibition mode. IR spectroscopy reveals displacement of the competitively‐bound azide by CO2, reflecting an interaction of both with the active site cofactor. This work comprises a proof‐of‐concept for a new approach to employ light for regulating the reaction of formate dehydrogenases and other CO2reductases.