FOR 1296:  Diversity of Asymmetric Thiamine Catalysis

• Subject Area: Chemistry ; Biology ; Medicine ; Thermal Engineering/Process Engineering
• Term: from 2010 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 128900243

Thiamine diphosphate (ThDP)-dependent enzymes catalyse a broad range of reactions, many still to be discovered, especially if non-physiological. The central aim of the Research Unit is to identify and introduce into practice new enzyme-catalysed transformations through a fundamental understanding of the diversity of asymmetric thiamine catalysis. In particular, it should be defined, which conditions are essential within the enzyme to enable one cofactor to catalyse many diverse reactions. Of particular interest here is the carboligating potential of ThDP-dependent enzymes for the asymmetric synthesis of chiral products yielding pharmaceutically interesting compounds. C-C bond forming reactions require a particular environment within the enzyme with well-defined donor or acceptor molecules that need to be positioned appropriately.
The analysis of sequence, structure and function of twelve specifically chosen enzymes, belonging to different families of ThDP-dependent enzymes, will allow the identification and modulation of the structure-function relationships. In this manner, superior parameters such as improved substrate specificity and stereoselectivity can be defined and implemented. Subsequently, the directed design of new biocatalysts could pave the way for new asymmetric syntheses, which are currently not yet feasible.
A thorough understanding of the structure-function relationship of ThDP-dependent enzymes is also significant for non-enzymatic catalysis and for theoretical considerations. New strategies in biomimetic organocatalysis could be developed to mimick the cofactor ThDP that has evolved in nature to catalyse a broad range of reactions. General parameters that stabilise intermediates in the enzyme or play a role in the activation of substrates can influence the development of optimised heterazolium catalysts. Likewise, potential transfer of N-heterocyclic carbene (NHC)-catalysed new reactions to enzymatic reactions is envisioned.
The selected ThDP-dependent enzymes will be characterised in depth under biochemical, mechanistic, kinetic and stereochemical aspects. Due to the heterogeneity of the class of ThDP-dependent enzymes and due to the low sequence similarity this part will be complemented by central bioinformatic and structural analysis.

• DFG Programme: Research Units

Projects

• Catalytic asymmetric Stetter reaction (Applicant Müller, Michael )
• Catalytic promiscuity of thiamine enzymes (Applicants Pohl, Martina ;  Rother, Dörte )
• Ketones and imines as substrates of ThDP-dependent enzymes (Applicant Müller, Michael )
• MenD (SEPHCHC synthase), a thiamine-dependent enzyme with similarity to the Stetterases (Applicant Sprenger, Georg )
• Modeling the sequence-structure-function relationships of ThDP-dependent enzymes (Applicant Pleiss, Jürgen )
• Reaction kinetics identification for the analysis of reaction mechanisms of ThDP-dependent enzymes (Applicant Spieß, Antje )
• Structure and reactivity of intermediates in the carboligation of ThDP-dependent enzymes (Applicant Tittmann, Kai )
• Thiamine-inspired novel organocatalytic reactions with heterazolium precatalysts (Applicant Zeitler, Kirsten )
• Zentralprojekt (Applicant Müller, Michael )

• Spokesperson: Professor Dr. Michael Müller