Didehydrofarnesyl diphosphate: an intrinsically fluorescent inhibitor of protein farnesyltransferase

Didehydrofarnesyl diphosphate (delta delta FPP), a fluorescent pentaene analogue of farnesyl diphosphate (FPP), was synthesized using stereoselective Wittig reactions. Although delta delta FPP was not an alternative substrate for yeast protein farnesyltransferase (FTase), the fluorescent analogue was a potent competitive inhibitor with a K(i) value of 8.8 microM (K (m) (FPP) = 27 microM).