Valentin Koehler

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Enzymatic catalysis and homogeneous catalysis offer complementary means to address synthetic challenges, both in chemistry and in biology. Despite its attractiveness, the implementation of concurrent cascade reactions that combine an organometallic catalyst with an enzyme has proven challenging because of the mutual inactivation of both catalysts. To(More)
Monoamine oxidase from Aspergillus niger (MAO-N) is a flavoenzyme that catalyses the oxidative deamination of primary amines. MAO-N has been used as the starting model for a series of directed evolution experiments, resulting in mutants of improved activity and broader substrate specificity, suitable for application in the preparative deracemisation of(More)
Direct activation of sp C H bonds a to a nitrogen atom represents an attractive strategy for functionalization of amines, especially those found in 5and 6-membered ring heterocycles. In particular, C H activation by oxidation, followed by nucleophilic addition, generates products of an overall oxidative Strecker orMannich process. Recent reports have(More)
The concurrent operation of multiple catalysts can lead to enhanced reaction features including (i) simultaneous linear multi-step transformations in a single reaction flask (ii) the control of intermediate equilibria (iii) stereoconvergent transformations (iv) rapid processing of labile reaction products. Enzymes occupy a prominent position for the(More)
Cytochrome P450 monooxygenases (P450s or CYPs) are a unique family of enzymes which are capable of catalysing the regio- and stereospecific oxidation of non-functionalised hydrocarbons. Despite the enormous synthetic potential of P450s, these enzymes have yet to be extensively employed for research purposes or in industry. Lack of stability, low activity,(More)
Artifical metalloenzymes combine the reactivity of small molecule catalysts with the selectivity of enzymes, and new methods are required to tune the catalytic properties of these systems for an application of interest. Structure-based computational design could help to identify amino acid mutations leading to improved catalytic activity and(More)
Stereoselectively labelled isotopomers of NAD(P)H are highly relevant for mechanistic studies of enzymes which utilize them as redox equivalents. Whereas several methods are firmly established for their generation in high diastereomeric purity by enzymatic methods, alternative methods have so far not been investigated. The article presents the(More)