Table 6.

Free energy penalty, ΔG_U, from formation of a disulfide bond calculated from theory and compared to experiment.

	ΔSxa (kcal mol−1 K−1)
I1	−0.033
I2	−0.050
I3	−0.051
N	−0.065
Loop Formation	ΔGU (kcal mol−1)
	Theoretical Valueb	Experimental Valuec
I1 to I2 60 °C	5.69	5.11 ± 0.8
I1 to I3 60 °C	5.99	6.01 ± 0.8
I2 to N 80 °C	5.29	4.87 ± 0.9
I3 to N 80 °C	4.94	3.97 ± 0.9
I1 to N 60 °C	10.66	10.18 ± 0.5

^a)Theoretical calculation of the entropy loss due to loop closure for each intermediate according to ref. (34)

^b)Theoretical ΔG_U = -TΔΔS_x at 60 ° or 80 °C and ΔΔS_x according to the loop formation indicated

^c)

Experimental ΔG_U for each Loop Formation according to the following equations:

$$\begin{array}{l}\mathrm{\Delta }{G}_U=\left[\mathrm{\Delta }{G}_{\mathit{\text{unf}}}{(<0)}_{I_2\underleftrightarrow{}\mathit{\text{or}}\underleftrightarrow{}{I}_3}-\mathrm{\Delta }{G}_{\mathit{\text{unf}}}{(<0)}_{I_1}\right]\text{At}60°\mathrm{C}\text{for}{\mathrm{I}}_1\text{to}{\mathrm{I}}_2{\text{or I}}_3\\ \mathrm{\Delta }{G}_U=\left[\mathrm{\Delta }{G}_{\mathit{\text{unf}}}{(>0)}_N-\mathrm{\Delta }{G}_{\mathit{\text{unf}}}{(<0)}_{I_2\underleftrightarrow{}\mathit{\text{or}}\underleftrightarrow{}{I}_3}\right]\mathrm{\text{at}}80°\mathrm{C}\text{for}{\mathrm{I}}_2\text{or}{\mathrm{I}}_3\text{to}\mathrm{N}\\ \mathrm{\Delta }{G}_U=\lfloor \mathrm{\Delta }{G}_{\mathit{\text{unf}}}{(>0)}_N-\mathrm{\Delta }{G}_{\mathit{\text{unf}}}{(<0)}_{I_1}\rfloor \text{at}60°\text{for}{\mathrm{I}}_1\text{to}\mathrm{N}\end{array}$$