Table 5 Energies (au) of the tetrapeptidic fragment of glucagon Asp-Tyr-Ser-Lys as calculated with ab initio calculations, using 3–21G and 6–31G*//3-21G basis sets

3-21G

6-31G*//3-21G

4a (containing Asp-Lys bridge)

−1713.92181

−1723.48502

4b (extended)

−1713.88362

−1723.44827

4c (containing a Lys-backbone H bond)

−1713.93222

−1723.47322

Energies (kcal/mol)

Solvation:

Relative: ΔE (3-21G)

ΔE(3-21G) + Solvation energy

ΔE(6-31G*//3-21G)

4a

−60.48

6.53

−53.95

0.0

4b

−29.97

30.49

.52

23.06

4c

−44.10

0.0

−44.10

7.41