TRICHODIENE SYNTHASE - SYNERGISTIC INHIBITION BY INORGANIC PYROPHOSPHATE AND AZA ANALOGS OF THE BISABOLYL CATION

A series of aza analogs of the bisabolyl and alpha-terpinyl cations were tested as inhibitors of the sesquiterpene cyclase, trichodiene synthase. Both (R)- and (S)-16 and (R)- and (S)-13 as well as trimethylamine were only weak inhibitors when incubated alone. In the presence of inorganic pyrophosphate, itself a known competitive inhibitor of trichodiene synthase, all five amines showed strong cooperative competitive inhibition with an enhancement factor estimated to be 10-40. The apparent induced inhibition constant alpha-K(j) decreased in going from trimethylamine to the monoterpene analogs 13 and was strongest for the sesquiterpene analogs 16, indicating that both electrostatic and hydrophobic interactions are important in the binding of each intermediate analog. The cyclase showed little discrimination, however, between the individual enantiomers of each inhibitor.