. Author manuscript; available in PMC: 2013 Oct 1.

Published in final edited form as: Biochim Biophys Acta. 2010 Mar 19;1798(6):1153–1163. doi: 10.1016/j.bbamem.2010.03.013

Table 2.

Binding affinity of 18-MC, ibogaine, and PCP for the Torpedo AChR in different conformational states.

Radioligand	NCA	Desensitized/CCh-bound state			Resting/α-BTx-bound state

		K_i^a (μM)	n_H^b	ΔG^c (kJ mol⁻¹)	K_i^a (μM)	n_H^b	ΔG^c (kJ mol⁻¹)
[³H]TCP	18-MC	0.17 ±0.01	1.11 ±0.07	−38.6 ±0.1	1.4 ±0.1	0.89 ± 0.06	−33.4 ±0.2
[³H]Ibogaine	18-MC	0.61 ± 0.08	1.02 ±0.13	−35.5 ±0.3	ND	ND	ND
[³H]18-MC	18-MC	0.47 ± 0.03	1.02 ±0.06	−36.1±0.2	1.0 ±0.1	0.70 ± 0.05	−34.3 ± 0.3
	Ibogaine	9.3 ± 0.6	1.11 ±0.07	−28.7 ±0.2	11 ±1	1.04 ±0.08	−28.3 ± 0.2
	PCP	0.41 ± 0.03	0.76 ± 0.03	−36.4 ±0.1	0.73 ± 0.05	0.88 ± 0.05	−35.0 ±0.2

ND, not determined.

Values were calculated from Fig. 3A–C ([³H]18-MC competition experiments), Fig. 4A ([³H]TCP competition experiments), and Fig. 4B ([³H]ibogaine competition experiments), respectively, using Eq. (3).

Hill coefficient.

Values were calculated using Eq. (4), at the experimental temperature (298K).