The 3D structure of a cyclosporin analogue in water is nearly identical to the cyclophilin-bound cyclosporin conformation

The conformation of [-MeSer³--Ser-(O-Gly⁸]CS, a water soluble cyclosporin derivative, has been determined in (D₆)DMSO and in water using NMR. In these polar solvents the conformation is identical and very similar to the structure found in the cyclophilin-cyclosporin complex. However, it differs significantly from its conformation in deuterated chloroform. This demonstrates unambiguously that the large structure change is induced primarily by the polar solvent rather than by complex formation with cyclophilin.