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 with two 1 4 intramolecular H‐bonds and represents the predominant (≥ 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 → cis isomerization of two X‐Pro peptide bonds.
|Number of pages||5|
|Journal||International journal of peptide and protein research|
|Publication status||Published - Oct 1977|
- proline peptides‐cyclic peptides‐prolin‐C‐nmr‐ring‐conformation‐complexones
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