C-13 NMR DETECTION OF DELOCALIZED C-10-ALLYLIC CATION IN THE BIOSYNTHESIS OF FARNESYL DIPHOSPHATE

A new signal was observed at delta 164.5 in the C-13 NMR spectrum obtained by the enzymatic condensation of [1-C-13]geranyl diphosphate with isopentenyl diphosphate by farnesyl diphosphate synthase; the signal was assigned to C-1 of a delocalized C-10-allylic cation on the basis of MO calculations, the C-13 NMR spectrum of [1-C-13]geraniol in magic acid (FSO3H-SbF5) and C-13 NMR spectra of the enzyme reaction under reversible inhibition conditions.