title: 6- and 14-Fluoro farnesyl diphosphate: mechanistic probes for the reaction catalysed by aristolochene synthase.
abstract: The catalytic mechanism of the enzyme aristolochene synthase from Penicillium roqueforti (PR-AS) has been probed with the farnesyl diphosphate analogues 6- and 14-fluoro farnesyl diphosphate (1a and 1c). Incubation of these analogues with PR-AS followed by analysis of the reaction products by GC-MS and NMR spectroscopy indicated that these synthetic FPP analogues were converted to the fluorinated germacrene A analogues 3b and 3c, respectively. In both cases the position of the fluorine atom prevented the formation of the eudesmane cation analogues 4b and 4c. These results highlight that germacrene A is an on-path reaction intermediate during PR-AS catalysis and shed light on the mechanism by which germacrene A is converted to eudesmane cation. They support the proposal that the role of PR-AS in the cyclisation is essentially passive in that it harnesses the inherent chemical reactivity present in the substrate by promoting the initial ionisation of farnesyl diphosphate and by acting as a productive template to steer the reaction through an effective series of cyclisations and rearrangements to (+)-aristolochene (7a).
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF103AT. UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Miller
authors.forename: Fanglei
authors.initials: F
authors.lastname: Yu
authors.forename: David W
authors.initials: DW
authors.lastname: Knight
authors.forename: Rudolf K
authors.initials: RK
authors.lastname: Allemann
mesh_terms: D002384:Catalysis; D003500:Cyclization; D005461:Fluorine; D008401:Gas Chromatography-Mass Spectrometry; D007535:Isomerases / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D015336:Molecular Probe Techniques; D010407:Penicillium / Q000201:enzymology; D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes / Q000138:chemical synthesis*; D045788:Sesquiterpenes, Germacrane
chemical_list: D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes; D045788:Sesquiterpenes, Germacrane; C054277:aristolochene; C471077:germacrene A; D005461:Fluorine; C004808:farnesyl pyrophosphate; D007535:Isomerases; C060050:aristolochene synthase