Figure 11.

Cyclo-(aAAAAA) and cyclo-(aAAAAA) were simulated using BE-META.²³⁹ D-amino acids are listed in lowercase and shown in red; N-methylated amino acids are underlined and shown in blue. In cyclo-(aAAAAA), residues 1 and 5 were N-methylated and the N-methylated amide bonds adopted a trans and cis configuration, respectively (denoted as t₁c₅). In cyclo-(aAAAAA), residues 1 and 6 were N-methylated and the two N-methylated amide bonds both adopted a trans configuration (denoted as t₁t₆). It was found that if the correct isomer states were given, the RSFF2 force field was able to reproduce the solution NMR structures for both cyclic peptides; however, when the correct isomer states were not given, the RSFF2 force field was unable to predict the t₁c₅ isomer of cyclo-(aAAAAA).