Length-Dependent Transition from Extended to Folded Shapes in Short Oligomers of an Azetidine-Based α-Amino Acid: The Critical Role of NH···N H-Bonds - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Molecules Année : 2023

Length-Dependent Transition from Extended to Folded Shapes in Short Oligomers of an Azetidine-Based α-Amino Acid: The Critical Role of NH···N H-Bonds

Résumé

Hydrogen bonds (H-bonds) are ubiquitous in peptides and proteins and are central to the stabilization of their structures. Inter-residue H-bonds between non-adjacent backbone amide NH and C=O motifs lead to the well-known secondary structures of helices, turns and sheets, but it is recognized that other H-bonding modes may be significant, including the weak intra-residue H-bond (called a C5 H-bond) that implicates the NH and C=O motifs of the same amino acid residue. Peptide model compounds that adopt stable C5 H-bonds are not readily available and the so-called 2.05-helix, formed by successive C5 H-bonds, is an elusive secondary structure. Using a combination of theoretical chemistry and spectroscopic studies in both the gas phase and solution phase, we have demonstrated that derivatives of 3-amino-1-methylazetidine-3-carboxylic acid, Aatc(Me) can form sidechain–backbone N–H···N C6γ H-bonds that accompany—and thereby stabilize—C5 H-bonds. In the capped trimer of Aatc(Me), extended C5/C6γ motifs are sufficiently robust to challenge classical 310-helix formation in solution and the fully-extended 2.05-helix conformer has been characterized in the gas phase. Concurrent H-bonding support for successive C5 motifs is a new axiom for stabilizing the extended backbone secondary structure in short peptides.
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hal-04234958 , version 1 (10-10-2023)

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Dayi Liu, Jean-Xavier Bardaud, Zeynab Imani, Sylvie Robin, Eric Gloaguen, et al.. Length-Dependent Transition from Extended to Folded Shapes in Short Oligomers of an Azetidine-Based α-Amino Acid: The Critical Role of NH···N H-Bonds. Molecules, 2023, 28 (13), pp.5048. ⟨10.3390/molecules28135048⟩. ⟨hal-04234958⟩
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