Table 2.

Modified rate constants^a involved in unstructured ensembles at 25 °C, pH 8.0.

	kfb	kfave,c	kintrad	krb	krave,c
k1	14	0.5	70.9	-	-
k2	-	-	-	2770	2770
k3	0.19	0.013	1.84	-	-
k4	-	-	-	14	7

^a)In units of M⁻¹min⁻¹

^b)k_f and k_r refer to observed rate constants for oxidation and reduction steps, respectively. k₁ and k₃ correspond to oxidations of R and 1S, respectively, while k₂ and k₄ correspond to the reductions of 1S and 2S, respectively.

^c)k_f^ave and k_r^ave are modified for statistical factors that arise from the oxidation or reduction of each member of the respective ensembles to give the average rate among all of the members of the ensembles. For k₁, there are 28 different ways to form the 1S ensemble from R, and therefore k₁ is divided by 28. For k₃, there are 15 ways to form the 2S ensemble from any member in the 1S ensemble, and therefore k₃ is divided by 15. In a similar manner for the rate constants corresponding to reductions, k₂ is not corrected because there is only one way to form R from any member of the 1S ensemble. k₄ is divided by 2 because there are two ways of forming a 1S species from any member of the 2S ensemble.

^d)k_intra is a rate constant (in min⁻¹) for a redox-independent, intramolecular disulfide reshuffling step during the oxidation of a disulfide bond using DTT^ox. It is determined by using the value 7.05 × 10⁻³ M⁻¹ for K_DTT (23, 26) in eq. 22, as discussed in the text.