Territrems: Naturally occurring specific irreversible inhibitors of acetylcholinesterase

Territrem B (TRB), a fungal metabolite isolated fromAspergillus terreus, potently and noncompetitively inhibited Electrophorus acetylcholinesterase (AChE EC 3.1.1.7), but had no inhibitory effect on horse serum butyrylcholinesterase (BtChE EC 3.1.1.8). The TRB-treated AChE did not recover its enzyme activity after either dialysis or dilution of the inhibited enzyme. The binding of ¹⁴C]TRB to AChE, but not to BtChE, was demonstrated. The concentrations of territrems required for 50% inhibition of AchE were: TRA 2.4 × 10^–8 M; TRB 1.9 × 10^–8 M; TRC 1.5 × 10^–8 M; TRA 9.8 × 10^–8 M; TRB 9.2 × 10^–8 M.