TABLE III.

Scheme 1* Parameters

	Rate Constants (s−1)
[Mg2+](mM)	γ0	δ0	δ1	δ2	δ3	δ4
0	3330	.0035	.091	1.9	22.6	101
10	2140	.0023	.061	4.9	163	71
100	1980	.0051	.098	8.6	265	94

Rate constants for the C_i-O_i transitions in Scheme 1* (Fig. 6 D) determined from fits to WT τ_K-V relations in 0-100 mM Mg²⁺ (Fig. 7 A), using equilibrium parameters from Table I (WT, WT_B). Since voltage sensor activation equilibrates rapidly, τ_K was fit by , where i represents the number of activated voltage sensors, δ_i and γ_i are forward and backward rate constants for the C_i-O_i transitions and pC_i, pO_i are conditional occupancies of the open and closed states (pC_i = p(C_i|C), pO_i = p(O_i|O)) (Horrigan et al., 1999). Forward rates (δ_i) were varied while backward rates were γ_i = δ_i/L₀Dⁱ and partial charges associated with these rate constants were z_δ = 0.165e and z_γ = −0.135e (Horrigan and Aldrich, 2002).