SUPPLEMENTARY INFORMATION FOR:
Thermodynamical Studies of the Example Peptide Containing
Metaaminobenzoic Acid (MABA) that Promotes Bends in 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 2 Standard 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 temperatures were
analyzed by using the following equation:
log10 (
K1
) = - DH ( 1 - 1 )𝑇21 )
K2
R ln10 T1 T2
where K1 and 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) )/
–1
ΔH(Ka(T2) ,Ka(T3) )/
kJ·mol–1
0.25
Ka1
8.31  10–5
1.1  10–4
1.32  10–4
kJ·mol
0.17
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
t = 25 °C
t = 40 °C
t = 50 °C
ΔH(Ka(T1),Ka(T2) ) /
Dag1_M
Ka
–1
ΔH(Ka(T2),Ka(T3) )/
kJ·mol–1
8.36
Ka1
1.66  10–4
9.77  10–5
1.91  10–7
kJ·mol
5.43
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