Synthesis of isotopically labelled terpene precursors for structure elucidation of terpenes and investigation of mechanistic aspects of their biosynthesis

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In this project several methylated analogs of the terpene monomers dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphat (IPP) will be synthesised. The obtained compounds will be coupled enzymatically to geranyl diphosphate (GPP), farnesyl diphosphate (FPP) or IPP using an FPP or GGPP synthase to obtain methylated analogs of FPP and geranylgeranyl diphosphate (GGPP) with one additional methyl group. Subsequently, also the incorporation of more than one additional methyl group will be tried. The products shall be dephosphorylated by a phosphatase, isolated and their structures will be elucidated by NMR spectroscopy. The obtained methylated acyclic terpene precursors will be converted into cyclic products using various terpene synthases. The formed terpenes will be isolated and their structures will be elucidated. Through this approach the naturally accessible structural space will be significantly expanded and our understanding of the plasticity of terpene synthases will be deepened. Furthermore, an already existing library of 13C-labelled terpene precursors will be extended to make all singly 13C-labelled isotopomers of methylated terpene analogs accessible by enzyme reactions. With the labelled compounds the cyclisation mechanisms of artificial terpenes and their EI-MS fragmentation mechanisms can be studied.