A threaded loop conformation adopted by a family of peptoid nonamers

Kai Huang, Cindy W. Wu, Tracy J. Sanborn, James A. Patch, Kent Kirshenbaum, Ronald N. Zuckermann, Annelise E. Barron, Ishwar Radhakrishnan

Research output: Contribution to journalArticlepeer-review


Non-natural polymers with well-defined three-dimensional folds offer considerable potential for engineering novel functions that are outside the scope of biological polymers. Here we describe a family of N-substituted glycine or "peptoid" nonamers that folds into an unusual "threaded loop" structure of exceptional thermal stability and conformational homogeneity in acetonitrile. The structure is chain-length-specific and relies on bulky, chiral side chains and chain-terminating functional groups for stability. Notable elements of the structure include the engagement of the positively charged amino terminus by carbonyl groups of the backbone through hydrogen bonding interactions and shielding of polar groups from and near-complete exposure of hydrophobic groups to solvent, in a manner resembling a folded polypeptide globular domain turned inside-out. The structure is stable in a variety of organic solvents but is readily denatured in any solvent/cosolvent milieu with hydrogen bonding potential. The structure could serve as a scaffold for the elaboration of novel functions and could be used to test methodologies for predicting solvent-dependent polymer folding.

Original languageEnglish (US)
Pages (from-to)1733-1738
Number of pages6
JournalJournal of the American Chemical Society
Issue number5
StatePublished - Feb 8 2006

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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