title: Evidence for the ionization steps in monoterpene cyclization reactions using 2-fluorogeranyl and 2-fluorolinalyl pyrophosphates as substrates.
abstract: Conversion of geranyl pyrophosphate to cyclic monoterpenes is considered to involve the preliminary isomerization of this acyclic precursor to enzyme-bound linalyl pyrophosphate and the cyclization of this tertiary intermediate. 2-Fluorogeranyl pyrophosphate and 2-fluorolinalyl pyrophosphate are effective competitive inhibitors of the cyclization of geranyl pyrophosphate by several different monoterpene cyclases, and the electron withdrawing alpha-fluorine substituent was shown to suppress the rate of cyclic product formation from both tritium-labeled analogs by at least two orders of cyclic These results indicate that both steps of the coupled isomerization-cyclization sequence are initiated by ionization of an allylic pyrophosphate, and they confirm the electrophilic nature of this enzymatic reaction type and its similarity to the prenyltransferase reaction.
mesh_terms: D003500:Cyclization; D007477:Ions / Q000378:metabolism; D007536:Isomerism; D007700:Kinetics; D010944:Plants / Q000378:metabolism; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D013379:Substrate Specificity; D013729:Terpenes / Q000378:metabolism*
chemical_list: D007477:Ions; D011106:Polyisoprenyl Phosphates; D013729:Terpenes; C051131:2-fluorolinalyl pyrophosphate; C017877:2-fluorogeranyl pyrophosphate