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Signature of n??* interactions in ?-helices.

ABSTRACT: The oxygen of a peptide bond has two lone pairs of electrons. One of these lone pairs is poised to interact with the electron-deficient carbon of the subsequent peptide bond in the chain. Any partial covalency that results from this n??* interaction should induce pyramidalization of the carbon (C'(i)) toward the oxygen (O(i-1)). We searched for such pyramidalization in 14 peptides that contain both ?- and ?-amino acid residues and that assume a helical structure. We found that the ?-amino acid residues, which adopt the main chain dihedral angles of an ?-helix, display dramatic pyramidalization but the ?-amino acid residues do not. Thus, we conclude that O(i-1) and C'(i) are linked by a partial covalent bond in ?-helices. This finding has important ramifications for the folding and conformational stability of ?-helices in isolation and in proteins.

SUBMITTER: Choudhary A

PROVIDER: S-EPMC3104237 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Signature of n→π* interactions in α-helices.

Choudhary Amit A Raines Ronald T RT

Protein science : a publication of the Protein Society 20110426 6

The oxygen of a peptide bond has two lone pairs of electrons. One of these lone pairs is poised to interact with the electron-deficient carbon of the subsequent peptide bond in the chain. Any partial covalency that results from this n→π* interaction should induce pyramidalization of the carbon (C'(i)) toward the oxygen (O(i-1)). We searched for such pyramidalization in 14 peptides that contain both α- and β-amino acid residues and that assume a helical structure. We found that the α-amino acid r ...[more]

PMID: 21442680

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