Polyproline II propensities from GGXGG peptides reveal an anticorrelation with β-sheet scales

Zhengshuang Shi, Kang Chen, Zhigang Liu, Angela Ng, W. Clay Bracken, Neville R. Kallenbach

Research output: Contribution to journalArticle

Abstract

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 AcGGXGGNH2 (X ≠ glycine), in equilibrium predominantly with β-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 ΔG values from the measured coupling constants of the backbone amides, we can construct a polyproline II scale that correlates negatively with β-sheet scales.

Original languageEnglish (US)
Pages (from-to)17964-17968
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number50
DOIs
StatePublished - Dec 13 2005

ASJC Scopus subject areas

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