Polyproline II propensities from GGXGG peptides reveal an anticorrelation with β-sheet scales Academic Article uri icon


MeSH Major

  • Models, Molecular
  • Peptides
  • Protein Folding
  • Protein Structure, Secondary


  • There is growing appreciation of the functional relevance of unfolded proteins in biology. However, unfolded states of proteins have proven inaccessible to the usual techniques for high-resolution structural and energetic characterization. Unfolded states are still generally conceived of as statistical coils, based on the pioneering work of Flory [(1969) Statistical Mechanics of Chain Molecules (Wiley, New York)] and Tanford [(1968) Adv. Protein Chem. 23, 121-282]. Recently, several lines of independent evidence have raised doubts about the random coil model and offer support for alternative views. Here, we show that polyproline II conformation is dominant in a host-guest peptide model AcGGXGGNH(2) (X not equal glycine), in equilibrium predominantly with beta-structure. This result is inconsistent with a random coil model and the general view that these peptides are unstructured. By calculating a set of apparent DeltaG values from the measured coupling constants of the backbone amides, we can construct a polyproline II scale that correlates negatively with beta-sheet scales.

publication date

  • December 13, 2005



  • Academic Article



  • eng

PubMed Central ID

  • PMC1312395

Digital Object Identifier (DOI)

  • 10.1073/pnas.0507124102

PubMed ID

  • 16330763

Additional Document Info

start page

  • 17964

end page

  • 8


  • 102


  • 50