Table 2. Comparison of the inhibition of Na_V1.3 by μ-BuIIIB and N-terminal analogs^a.

Peptide	kon (μM•min)-1	koff (min1)	Kd (μM)
μ-BuIIIB	0.085 ± 0.01	0.017 ± 0.007	0.2 ± 0.086
[Ala1]BuIIIB	0.014 ± 0.004	0.01 ± 0.003	0.71 ± 0.3
[d-Ala2]BuIIIB	0.83 ± 0.05	0.004 ± 0.0017	0.0048 ± 0.002
[Ala2]BuIIIB	0.25 ± 0.03	0.009 ± 0.002	0.036 ± 0.009
[Ala3]BuIIIB	0.46 ± 0.03	0.007 ± 0.0013	0.015 ± 0.003
[Ala4]BuIIIB	0.056 ± 0.008	0.01 ± 0.002	0.18 ± 0.044
[des1-4]BuIIIB	0.47 ± 0.06	0.025 ± 0.005	0.053 ± 0.013

^aRate constants were determined as described in Methods. K_d was determined from k_off/k_on. Data for μ-BuIIIB are from Wilson et al.(20)