Conformational studies of peptides containing cis-3-hydroxy-D-proline

Area of Science:

• Peptide Chemistry
• Structural Biology
• Organic Chemistry

Background:

• The three-dimensional structure of peptides is crucial for their biological function.
• Amino acid modifications can significantly alter peptide conformation.
• cis-3-hydroxy-d-proline (d-cis-3-Hyp) is a proline analog with a hydroxyl group at the 3-position.

Purpose of the Study:

• To investigate the role of the 3-hydroxyl group of d-cis-3-Hyp in peptide conformation.
• To determine how protection and deprotection of the 3-hydroxyl group affect peptide structure.
• To analyze the impact of solvent polarity on peptide structures containing d-cis-3-Hyp.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy was employed for conformational analysis.
• Peptides containing protected and deprotected d-cis-3-Hyp were synthesized.
• Comparative studies were performed in different solvents (CDCl(3) and DMSO-d(6)).

Main Results:

• Peptides with protected d-cis-3-Hyp adopted a stable beta-hairpin structure in both solvents.
• Deprotection of the 3-hydroxyl group in a polar solvent (DMSO-d(6)) disrupted the beta-hairpin.
• A pseudo beta-turn-like nine-membered ring structure formed in the deprotected peptide in DMSO-d(6) via an intramolecular hydrogen bond.

Conclusions:

• The 3-hydroxyl group of d-cis-3-Hyp is critical for maintaining beta-hairpin structures in polar environments.
• Solvent polarity plays a key role in the conformational preferences of peptides containing d-cis-3-Hyp.
• Intramolecular hydrogen bonding involving the 3-hydroxyl group can dictate peptide secondary structure.