title: Synthesis and evaluation of chlorinated substrate analogues for farnesyl diphosphate synthase.
abstract: Substrate analogues for isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), where the C3 methyl groups were replaced by chlorine, were synthesized and evaluated as substrates for avian farnesyl diphosphate synthase (FPPase). The IPP analogue (3-ClIPP) was a cosubstrate when incubated with dimethylallyl diphosphate (DMAPP) or geranyl diphosphate (GPP) to give the corresponding chlorinated analogues of geranyl diphosphate (3-ClGPP) and farnesyl diphosphate (3-ClFPP), respectively. No products were detected in incubations of 3-ClIPP with 3-ClDMAPP. Incubation of IPP with 3-ClDMAPP gave 11-ClFPP as the sole product. Values of K(M)(3-ClIPP) (with DMAPP) and K(M)(3-ClDMAPP) (with IPP) were similar to those for IPP and DMAPP; however, values of k(cat) for both analogues were substantially lower. These results are consistent with a dissociative electrophilic alkylation mechanism where the rate-limiting step changes from heterolytic cleavage of the carbon-oxygen bond in the allylic substrate to alkylation of the double bond of the homoallylic substrate.
authors.affiliation: Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, Utah 84112, USA.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Heaps
authors.forename: C Dale
authors.initials: CD
authors.lastname: Poulter
mesh_terms: D000818:Animals; D051228:Geranyltranstransferase / Q000737:chemistry / Q000378:metabolism*; D054879:Halogenation; D045782:Hemiterpenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D045782:Hemiterpenes; D009943:Organophosphorus Compounds; C004809:isopentenyl pyrophosphate; C043060:3,3-dimethylallyl pyrophosphate; D051228:Geranyltranstransferase