Trichodiene Synthase: Synthesis and Inhibition Kinetics of 12‐Fluoro‐farnesylphosphonophosphate for Sesquiterpene Cyclases

trans, trans ‐Farnesyl diphosphate (FPP) serves as a universal substrate for a large family of sesquiterpene cyclases that are responsible for biosynthesis of more than 300 structurally diverse sesquiterpenes in nature. A new FPP substrate analogue, 12‐fluoro‐farnesylphosphonophosphate (12‐F‐F‐CH 2 PP), was synthesized in this paper for applications on kinetic and mechanistic studies of the enzyme family. Trichodiene synthase (TS), a sesquiterpene cyclase, catalyzes the conversion of trans, trans ‐farnesyl diphosphate (FPP) to trichodiene. 12‐F‐F‐CH 2 PP was tested as a potential inhibitor of TS. Inactivation and inhibition kinetic experiments showed that 12‐F‐F‐CH 2 PP was not a mechanism‐based inactivator for TS; instead, a mixed‐type reversible inhibition was observed with inhibition constants K i1 = 2.33 ± 0.50 μM and K i2 = 25.80 ± 7.70 μM, values close to those previously determined for farnesylphosphonophosphate, K i1 = 3.25 μM and K i2 = 9.10 μM. Although 12‐F‐F‐CH 2 PP did not irreversibly inactivate TS, this new analogue serves as a potential active‐site directed inactivator and mechanistic probe of other sesquiterpene cyclases and FPP‐utilizing enzymes, which utilize FPP as a common acyclic substrate.