Incorporation of a potentially helix breaking D-Phe-Pro sequence into the center of a right handed 16 residue peptide helix.
Non protein amino acids with strong secondary structure preferences are potentially useful in peptide design. alpha-Aminoisobutyric acid (Aib) is a powerful 'stereochemical director' of polypeptide chain folding, stabilizing helical conformations in diverse oligopeptide sequences. In an approach to the de novo design of alpha,alpha motifs, the 16 residue peptides Boc-Val-Ala-Leu-Aib-Val-Ala-Leu-Xxx-Pro-Val-Ala-Leu-Aib-Val-Ala-Leu-OMe (Xxx = D-Phe 1; Xxx = L-Phe 2) have been spectroscopically studied in solution. Analysis of nuclear Overhauser effects, delineation of solvent shielded NH groups and circular dichroism spectra establish helical conformations in both the peptides. Despite the presence of a potentially helix breaking, central, (D)Phe-(L)Pro segment, peptide 1 is forced into a continuous helical fold presumably as a consequence of the overriding stereochemical dominance of the Aib residues.
Molecular Biophysics Unit, Indian Institute of Science, Bangalore.
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Gurunath
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Balaram
D000595:Amino Acid Sequence; D000621:Aminoisobutyric Acids; D002942:Circular Dichroism; D004151:Dipeptides / Q000737:chemistry*; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D010649:Phenylalanine; D011392:Proline; D017433:Protein Structure, Secondary
D000621:Aminoisobutyric Acids; D004151:Dipeptides; D009842:Oligopeptides; D010455:Peptides; C100049:2-aminoisobutyric acid; D010649:Phenylalanine; C088360:phenylalanylproline; D011392:Proline