Hi, I am Chris.

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During my PhD, I have worked on enzymes involved in steroid degradation in anaerobic, denitrifying bacteria. Steroids are ubiquitous, many of which have endocrine disrupting or carcinogenic properties. While aerobic steroid degrading bacteria mainly use oxygen-dependent mono- and dioxygenases to activate the steroid side-chain, we identified an ATP-dependent enzyme cascade in our model organism Sterolibacterium denitrificans, which allows for the activation of the steroid side-chain under oxygen-independent conditions. In related projects, I am studying enzymes involved in the activation of the steroid side chain of phyto- and mycosterols, as well as key enzymes of androgens and estrogens steran skeleton degradation. During estrogen degradation, a non-radical SAM- and cobalamin-dependent methyltransferase from Denitratisoma oestradiolicum catalyses the conversion of estrogens into androgens, a unique reaction in nature. I apply various chromatographic methods for the isolation of previously unknown enzymes (affinity chromatography, size exclusion such, anion exchange chromatography among others) and UPLC(-MS), GC for the identification of steroid-derived metabolites.