The conformation of the cyclic nonapeptide from linseed, cyclolinopeptide A in
methanol and in acetonitrile has been elucidated by one- and two-dimensional nuclear
magnetic resonance. The molecule is folded in a ß-turn conformation. Cyclolinopeptide A
interacts and weakly complexes with Tb3+ (a Ca2+ mimic ion) with the metal ion
positioned proximally to the Phe residue, but with no substantial structural alteration upon
metal binding. Cyclolinopeptide A is also seen to aid the translocation of Pr3+ (another
Ca2+ mimic) across unilamellar liposomes. However, cyclolinopeptide A does not phase
transfer or act as an ionophore of calcium ion myself. Experiments using lanthanide ions thus
do not necessarily indicate any ionophoretic ability of the complexone towards calcium
ions
