The crystal structure shows that the acid/base pair in the active site - the cysteine and the glutamate - are located on opposite sides of the active site, implying that a proton is added on one side ...The crystal structure shows that the acid/base pair in the active site - the cysteine and the glutamate - are located on opposite sides of the active site, implying that a proton is added on one side of the molecule and removed from the other. The protein prenyltransferase reaction and the isoprenoid chain elongation reactions are very similar: the electrophile is the same, but in the former the nucleophile is a thiolate, while in the latter the nucleophile is a pi bond.
