Water dependent alkyl dehydrogenases


Hi I am Ralf,

I am working on water dependent hydroxylases of molybdenum-cofactor containing dimethyl sulfoxide reductases (DMSOR) enzyme family from anaerobic bacteria. They are involved in the degradation processes of many toxic compounds, such as steroids, aromatics or even alkanes under anaerobic conditions. I am developing enzyme assays to follow the mechanism of such water insoluble compounds in an aqueous environment. For substrate identification I apply various chromatographic methods, such as UPLC or GC and for valid mass identification I am using high-resolution mass spectrometry. The structural composition of Mo-cofactor containing hydroxylases is elucidated with heterologously produced enzymes enrichment enzymes via cryo electron-microscopy in collaboration with Petra Wendler, University of Potsdam. The structural information is  a prerequisite to link tailored enzymes to inorganic electrode materials (biohybrids) for biocatalytic processes with potential application for industrial processes.

Hi I am Dennis,

Together with Ralf I am working on different molybdenum cofactor-containing oxidoreductases of the DMSOR family that catalyse hydroxylation reactions of hydrophobic substrates. Starting with the steroid C25 dehydrogenase (S25DH) from the denitrifying Sterolibacterium denitrificans, my aim is to design and produce tailored enzyme variants for an optimal interaction with provided inorganic electrodes, while maintaining their catalytic activity. We collaborate with the Nanomaterials Research Group of Anna Fischer (University of Freiburg). During further investigations, we also focus on the optimization of the whole cell catalysis with S25DH-producing Thauera aromatica cells for the formation of cell/electrode-biohybrids. Since the S25DH is able to convert vitamin D3 (cholecalciferol) to the clinically highly interesting 25-OH-vitamin D3 (calcidiol), this biological, enzymatic production system could be of great interest for future biotechnological applications.

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Linking water-dependent hydroxylases with an active site molybdenum-cofactor to inorganic electrode materials for electrocatalytic applications


Transformation of VitD3 to 25-OH-VitD3 by Thauera aromatic cells, heterologously producing S25DH1. In the presence of 2-hydroxypropyl-β-cyclodextrin (HPCD), VitD3 isomerizes to preVit3 that serves as substrate for the periplasm-located, S25DH1-catalyzed hydroxylation reaction. In vitro, electrons that are released during the oxidation reaction can be transferred to Fe(CN)63+, subsequently being regenerated by a extracellular electrode.