Table 1.

Comparison of the kinetics parameters of KIIIA and it disulfide-deficient analogs in blocking Na_V1.2 and Na_V1.4

Analog	NaV1.2					NaV1.4
	%[a] Block	kobs (min-1)	koff (min-1)	kon [b] (μM•min)-1	Kd [c] (μM)	% Block	kobs (min-1)	koff (min-1)	kon [b] (μM•min)-1	Kd [c] (μM)
KIIIA	90±3	0.36±0.06	0.0016±0.0016	0.36±0.06	0.004±0.004	86±6	0.91±0.17	0.05±0.017	0.86±0.17	0.06±0.02
KIIIA[C1A, C9A]	93±2	1.8±0.39	0.014±0.002	1.8±0.39	0.008±0.002	85±2	4.0±0.5	0.78±0.1	3.22±0.51	0.24±0.05
KIIIA[C2A, C15A]	66±4	0.07±0.02	0.01±0.0014	0.06±0.02	0.17±0.06	71±4	0.56±0.08	0.15±0.03	0.41±0.09	0.37±0.11
KIIIA[C4A, C16A]	8±3	n.a. [d]	n.a.	--	--	1±1	n.a.	n.a.	--	--

^[a]Percent block was determined at steady-state or plateau value of single exponential fit of time course of block during 20 min. of exposure to 1 μM peptide;

^[b]k_on was estimated from {k_obs – k_off};

^[c]K_d was estimated from {k_off/k_on};

^[d]n.a., unable to be determined because level of block was too small. Values represent mean s.d. from at least three different oocytes.