Table II.

Cooperative competitive inhibition of trichodiene synthase by inorganic pyrophosphate (PP_i) and quaternary ammonium analogues of the bisabolyl carbocation intermediate

inhibitor	PPi	inhibitor
	KI (μM)	αKJa (μM)
PPi b	0.49	-
trimethylamine b	0.68	172.0
BTAC	0.7	36
α-terpinyl cation analogue b	0.48	10.9
R-azabisabolene b	0.51	2.6
S-azabisabolene b	0.47	2.9

^aCalculated induced inhibition constant of the ammonium analogues (Figure 2) in the presence of PP_i, using equation (1) for cooperative competitive inhibition [10, 25].

^bFrom reference 10.