PMID: 591178Oct 1, 1977

Conformations of proline-containing cyclic peptides. 1H and 13C n.m.r. evidence for a solvent stabilized All-Cis X-Pro conformer of Cyclo-(Pro-Gly-Gly-Pro)2

International Journal of Peptide and Protein Research
M HollosiT Wieland

Abstract

As inferred from 13C, 1H n.m.r. data, CD measurements and ion-binding experiments, the title molecule can assume two major C2 symmetric conformations. One of these has an all-trans X-Pro peptide backbone and two 1 comes from 4 intramolecular H-bonds and represents the predominant (greater than or equal to 95%) form in D2O and nonpolar (CD3CN) solvents. Stabilized by specific solvent-solute interactions, the other conformer becomes competitive (45%) in DMSO solution. It is shown to possess a four-cis X-Pro skeleton and no intramolecular H-bonds. The Mg++ complex of the cyclic peptide in CD3CN is again C2 symmetric and its formation proceeds via a slow trans leads to cis isomerization of two X-Pro peptide bonds.

Related Concepts

Circular Dichroism, Vibrational
Glycine, Sodium Hydrogen Carbonate
Hydrogen Bonding
In Vivo NMR Spectroscopy
Cyclic Peptides
Proline

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