Table 3.

Fraction of ternary complex formed (FTCF), apparent k_on for the reaction peptide + alkaloid·Na_V → peptide·alkaloid·Na_V, and k_on for the reaction peptide + Na_V → peptide·Na_V, corresponding to k_BC and k_RA of Fig. 1C, respectively

Peptide	Alkaloid	FTCF†	Apparent kon, min−1·μM−1†	kon, min−1·μM−1‡
KIIIA[K7A]	TTX	0.48 ± 0.08	0.16 ± 0.02	—
KIIIA[K7A]	STX	0.46 ± 0.07	0.15 ± 0.02	—
KIIIA[K7A]	GTX2/3	0.30 ± 0.07	0.09 ± 0.03	—
KIIIA[K7A]	None	—	—	0.13 ± 0.006
KIIIA	TTX	0.56 ± 0.03	0.20 ± 0.01	—
KIIIA	STX	—	0.09 (0.03–0.3)§	—
KIIIA	GTX2/3	0.31 ± 0.03	0.10 ± 0.01	—
KIIIA	None	—	—	0.30 ± 0.030

Values are means ± SD, n ≥3 oocytes, except for the following.

^§Values in parentheses, which span a decade, indicate proposed limits of uncertainty for k_on; see Fig. 4, C and D.

^†From results for formation of ternary complex illustrated in Fig. 4, A and B, processed as described in methods.

^‡From slope of k_obs versus [peptide] for formation of binary peptide·NaV complex, from Zhang et al. (2009).