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Conformational analysis of two cyclic disulfide peptides.
C García-Echeverría1, G Siligardi, P Mascagni
1Department of Organic Chemistry, University of Barcelona, Spain.
Biopolymers
|June 1, 1991
Summary
Nuclear Magnetic Resonance (NMR) and Circular Dichroism (CD) studies reveal that two cyclic tetrapeptides form stable beta-turn structures. Their disulfide bond stereochemistry differs, yet peptide chirality is preserved.
Area of Science:
- Peptide Chemistry
- Structural Biology
- Spectroscopy
Background:
- Cyclic peptides containing disulfide bonds are crucial in medicinal chemistry.
- Beta-turns are important secondary structures influencing peptide conformation and function.
- Understanding disulfide bond stereochemistry is key to peptide structure-activity relationships.
Purpose of the Study:
- To investigate the formation and stabilization of beta-turn structures in two cyclic tetrapeptides.
- To determine the stereochemistry of the disulfide linkage in these peptides.
- To explore the influence of solvent on peptide conformation.
Main Methods:
- Complete Nuclear Magnetic Resonance (NMR) studies.
- Circular Dichroism (CD) spectroscopy.
- Quantitative Nuclear Overhauser Effect (NOE) data analysis.
Main Results:
- Both cyclic tetrapeptides (Ac-L-Pen-L-Pro-D-Val-L-Cys-NH2 and Ac-L-Cys-L-Pro-D-Val-L-Cys-NH2) adopt a type II beta-turn conformation.
- NMR and CD data indicate distinct dihedral angles for the disulfide bridge in the two peptides.
- Peptide chirality is maintained despite differences in disulfide bond stereochemistry.
Conclusions:
- The study elucidates the conformational preferences of cyclic tetrapeptides with disulfide bonds.
- Solvent-dependent structural investigations provide insights into peptide stability.
- The findings contribute to the understanding of disulfide bond stereochemistry and its impact on peptide structure.