Cyclo-linopeptide B methanol tris-olvate

Area of Science:

• Biochemistry
• Structural Biology
• Natural Products Chemistry

Background:

• Cyclo-linopeptides are cyclic peptides found in natural sources.
• Flaxseed oil is a potential source of bioactive compounds.
• Understanding peptide structure is crucial for elucidating function.

Purpose of the Study:

• To isolate and characterize a novel cyclo-linopeptide from flaxseed oil.
• To determine the three-dimensional structure and conformation of the isolated peptide.
• To investigate the stabilizing interactions within the peptide structure.

Main Methods:

• Isolation of the cyclo-linopeptide from flaxseed oil.
• Determination of amino acid configuration using the CORN rule.
• X-ray crystallography to elucidate the crystal structure.
• Analysis of peptide bond configurations (cis/trans) and hydrogen bonding patterns.

Main Results:

• Isolation and identification of cyclo(Met-Leu-Ile-Pro-Pro-Phe-Phe-Val-Ile) (CLP-B) as a methanol tris-olvate.
• All nine amino acid residues were confirmed to be in the l-configuration.
• The cyclic nonapeptide exhibited eight trans and one cis peptide bond between proline residues.
• The conformation was stabilized by an α-turn and two β-turns, involving specific N-H⋯O hydrogen bonds.
• Crystal structure revealed intermolecular N-H⋯O and O-H⋯O hydrogen bonds forming chains parallel to the a axis.

Conclusions:

• CLP-B is a novel cyclo-linopeptide isolated from flaxseed oil with a defined secondary structure.
• The specific arrangement of amino acids and hydrogen bonds dictates the peptide's conformation.
• The crystal packing is influenced by extensive hydrogen bonding, suggesting potential intermolecular interactions in biological systems.