Fig. 1

Structure of cyclosporin and scheme depicting the sequence of residues. a DFT-optimized structure of cyclosporin. Nitrogen, oxygen, carbon and proton atoms are shown in blue, red, grey and white, respectively. Hydrogen bonds are represented by dashed lines. b Schematic representation of the structure of (a) where the relevant residues are shown. H-bonds are depicted by dashed lines. The two parallel dashed lines indicate an antiparallel β-pleated sheet structure. The D-Ala8 residue has an absolute (R) configuration, and there is a cis-amide linkage between Me-Leu9 and Me-Leu10