Fig. 2.
(a) Bisabolyl carbocation intermediate in trichodiene synthase catalysis. (b) R-Azabisabolene, a cationic analogue of the bisabolyl cation in the trichodiene synthase mechanism, is a strong competitive inhibitor in the presence of inorganic diphosphate (PPi) with Ki for PPi = 0.51 μM and an induced inhibition constant of 2.6 μM [10]. (c) The aza analogue of the α-terpinyl cation is a competitive inhibitor in the presence of inorganic pyrophosphate (PPi) with Ki for PPi = 0.48 μM and an induced inhibition constant of 10.9 μM [10]. (d) The benzyl triethylammonium cation (BTAC) is a phase transfer catalyst for synthetic organic chemistry that partially mimics the bisabolyl carbocation intermediate (a).