Table 5.

Results of Scheme 4 fitted to TMA- or choline-activated human muscle acetylcholine nicotinic single-channel data

	TMA, −80 mV		Choline, −80 mV
	Rate constant	±CV (%)	Rate constant	±CV (%)
α1 (s−1)	1550	35	7880	8
β1 (s−1)	122	47	3	16
α2 (s−1)	2540	7	4770	22
β2 (s−1)	70 200	6	62 900	39
αB (s−1)	541	18	519	20
βB (s−1)	699	16	17	14
k+Bs (m−1 s−1)	1530	99	225	50
k−Bs (s−1)	0.369	98	0.00648	56
k+2o (m−1 s−1)	4.65 × 108	95	21	13
k−2o (s−1)	76 600	97	0.000292	11
k+1=k+2 (m−1 s−1)	6.24 × 105	12	3.32 × 104	35
k−1=k−2 (s−1)	7310	8	14800	34
E1=β1/α1	0.10	29	0.00044	21
E2=β2/α2	28	5	14	10
EB=βB/αB	1.5	26	0.036	18
KB=k−B/k+B (mm)	10	fixed	10	fixed
KBs=k−Bs/k+Bs (μm)	550	31	27	25
KDo=k−2o/k+2o (μm)	47	35	14	10
KD=k−1/k+1=k−2/k+2 (mm)	12	7	473	13

Scheme 4 has 14 parameters in total but only 10 of them are free to fit (two are calculated from detailed microscopic reversibility and two are constrained as a result of the assumption that the two binding sites are equivalent and independent). Estimates of rate constants are averages of fits to three (choline) or four (TMA) data sets, with the appropriate CV from replicates. The estimates of the equilibrium constants are averages of the values obtained from the ratio of the appropriate rate constants for each separate fit.