Fig. 7.

The potential energy surface, E = f(φ,ψ), for Ac–l–Ala–Tzl(4–Me) calculated by M06–2X/6–311++G(d,p) method in vacuo with solid-state crystal structure conformations of thiazole–amino acid residues (pink square) and oxazole–amino acid residues (blue triangular) retrieved from the Cambridge Structural Database. Energy contours are plotted every 1 kcal/mol