SUPPLEMENTARY INFORMATION FOR:

Thermodynamical Studiesofthe ExamplePeptideContainingMetaaminobenzoic Acid (MABA) thatPromotes Bendsin Proteins

Joanna Makowska · Dorota Uber · Lech Chmurzyński

Section S1 Potentiometric Titration Curves of Dag1 and Dag1_M

(A)

(B)

Fig. 1S Potentiometric-titration curves of peptides Dag1 (A) and Dag1_M (B) in water at 25 °C (triangles), 30 °C (bullets), and 40 °C (squares) and the curves obtained by fitting the experimental data with the equilibrium model (lines).

Section 2Standard Molar Enthalpies Corresponding to All Stages of Proton Exchange with Water of Dag1 and Dag1_M

For the sake of completeness, we report here the values of the standard molar enthalpies of proton exchange with water corresponding to all protonation stages of Dag1 and Dag1_M. The values of ΔH for Dag1 and Dag1_M at three different temperatureswere analyzed by using the following equation:

whereK1and K2 are the acidity constants at absolute temperatures T1 and T2, respectively, H is the enthalpy (assigned to T1), and R is the universal gas constant.

Dag1

Ka / t = 25oC / t = 30°C / t = 40°C / ΔH(Ka(T1), Ka(T2) )/kJ·mol–1 / ΔH(Ka(T2) ,Ka(T3) )/kJ·mol–1
Ka1 / 8.3110–5 / 1.110–4 / 1.32  10–4 / 0.17 / 0.25
Ka2 / 1.2310–8 / 1.1710–8 / 1.70 10–8 / 0.08 / 0.50
Ka3 / 6.0310–11 / 4.5710–11 / 6.92 10–11 / 0.38 / 0.58

Dag1_M

Ka / t = 25°C / t = 40°C / t = 50°C / ΔH(Ka(T1),Ka(T2) ) /kJ·mol–1 / ΔH(Ka(T2),Ka(T3) )/kJ·mol–1
Ka1 / 1.6610–4 / 9.7710–5 / 1.9110–7 / 5.43 / 8.36
Ka2 / 1.7810–8 / 2.9510–8 / 1.0710–8 / 0.42 / 1.25
Ka3 / 1.2510–10 / 1.0710–9 / 3.8910–9 / 0.25 / 0.88