Cyclo­linopeptide B methanol tris­olvate

The title compound, C₅₆H₈₃N₉O₉S·3CH₃OH, is a methanol tris­olvate of the cyclo­linopeptide cyclo(Met¹—Leu²—Ile³—Pro⁴—Pro⁵—Phe⁶—Phe⁷—Val⁸—Ile⁹) (henceforth referred to as CLP-B), which was isolated from flaxseed oil. All the amino acid residues are in an L-configuration based on the CORN rule. The cyclic nona­peptide exhibits eight trans peptide bonds and one cis peptide bond observed between the two proline residues. The conformation is stabilized by an α-turn and two consecutive β-turns each containing a N—H...O hydrogen bond between the carbonyl group O atom of the first residue and the amide group H atom of the fourth (α-turn) or the third residue (β-turns), repectively. In the crystal, the components of the structure are linked by N—H...O and O—H...O hydrogen bonds into chains parallel to the a axis.