Figure 10

ΔG expressed as a function of the fractional extension for the neck linker, Ala-only peptide, no-Asparagine chain (Asn substituted), no-Lysine chain (Lys substituted) and no-Proline chain (Pro substituted). Fractional extension is defined as a ratio of the extension measured from the relaxed mean end-to-end distance to the rest of the path (L minus the relaxed mean end-to-end distance, where L is the contour length of the chain in question). The contour length per amino acid has been assumed to be equal to 4.0 Å⁶⁵. Several different ΔG values have been acquired by repeating the in silico experiments while using different values of a constant stretching force equal to 130, 400, 700, 1000 and 1300 kJ*mol⁻¹*nm⁻¹. Parabolic curves have been fitted to the plots. Quadratic coefficients of fitted plots are: Lys substituted: 44.3 * 10³k_BT; neck linker: 10.1 * 10³k_BT; Asn substituted: 9.2 * 10³k_BT; Pro substituted: 7.9 * 10³k_BT; Ala-only: 5.4 * 10³k_BT. They represent the effective stiffness of the stretched structure. The intercept coefficients are:  −37.3,  −95.8,  −86.6,  −134.4 and  −63.1 k_BT, respectively.