Inherent Conformational Preferences of Ac‐Gln‐Gln‐NHBn: Sidechain Hydrogen Bonding Supports a β‐Turn in the Gas Phase. (24th October 2016)

• Record Type: Journal Article
• Authors: Walsh, Patrick S.; Blodgett, Karl N.; McBurney, Carl; Gellman, Samuel H.; Zwier, Timothy S.
• Is Part Of: Angewandte Chemie. Volume 128:Number 47(2016)
• Page Start: 14838
• Page End: 14842
• Publication Date: 2016-10-24
• Subjects: Dichtefunktionalrechnungen -- Gasphasenchemie -- Glutamin -- IR-Spektroskopie -- Überschallexpansion; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201607842
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Gas‐phase single‐conformation spectroscopy is used to study Ac‐Gln‐Gln‐NHBn in order to probe the interplay between sidechain hydrogen bonding and backbone conformational preferences. This small, amide‐rich peptide offers many possibilities for backbone–backbone, sidechain–backbone, and sidechain–sidechain interactions. The major conformer observed experimentally features a type‐I β‐turn with a canonical 10‐membered ring C=O—H−N hydrogen bond between backbone amide groups. In addition, the C=O group of each Gln sidechain participates in a seven‐membered ring hydrogen bond with the backbone NH of the same residue. Thus, sidechain hydrogen‐bonding potential is satisfied in a manner that is consistent with and stabilizes the β‐turn secondary structure. This turn‐forming propensity may be relevant to pathogenic amyloid formation by polyglutamine segments in human proteins.