Conformational preference of polyglycine in solution to elongated structure

Satoshi Ohnishi, Hironari Kamikubo, Masayoshi Onitsuka, Mikio Kataoka, David Shortle

Research output: Contribution to journalArticle

Abstract

Do polypeptide chains ever behave like a random coil? In this report we demonstrate that glycine, the residue with the fewest backbone restrictions, exhibits a strong preference for an extended conformation in solution when polymerized in short segments of polyglycine. A model peptide system comprised of two unique tripeptide units, between which 1 to 18 glycine residues are inserted, is characterized by NMR and by small-angle X-ray scattering (SAXS). The residual dipolar coupling (RDC) values of the two tripeptide units are insensitive to changes in number of intervening glycines, suggesting that extension of the linker does not alter the average angular relationship between the tripeptides. Polyglycine segments longer than nine residues form insoluble aggregates. SAXS measurements using synchrotron radiation provide direct evidence that polyglycine peptides adopt elongated conformations. In particular, the construct with a linker with six glycines showed a scattering profile indicative of a monomeric state with a radius of gyration and the maximum dimension of 9.1 Å and ∼34 Å, respectively. The ensemble averaged global structure of this 12-mer peptide can best be approximated by a cylinder with a radius of 4 Å and a length of ∼33 Å, making it intermediate in extension between a β strand and an α helix.

Original languageEnglish (US)
Pages (from-to)16338-16344
Number of pages7
JournalJournal of the American Chemical Society
Volume128
Issue number50
DOIs
StatePublished - Dec 20 2006

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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