University of Illinois Urbana-Champaign

Conformation-specific infrared and ultraviolet spectroscopy of cold [YAPAA+H]+ and [YGPAA+H]+ ions: A stereochemical 'twist' on the β-hairpin turn

DeBlase, Andrew F.

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2314.pdf
849238.pptx

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https://hdl.handle.net/2142/97149

Description

Title
Conformation-specific infrared and ultraviolet spectroscopy of cold [YAPAA+H]+ and [YGPAA+H]+ ions: A stereochemical 'twist' on the β-hairpin turn
Author(s)
DeBlase, Andrew F.
Contributor(s)
  • Zwier, Timothy S.
  • McLuckey, Scott A.
  • Burke, Nicole L.
  • Lawler, John T.
  • Harrilal, Christopher P.
Issue Date
2017-06-23
Keyword(s)
Ions
Date of Ingest
  • 2017-07-27T20:15:52Z
  • 2018-01-29T23:06:09Z
Abstract
Incorporation of the unnatural D-proline ($^{D}$P) stereoisomer into a polypeptide sequence is a typical strategy to encourage formation of $beta$-hairpin loops because natural sequences are often unstructured in solution. Using conformation-specific IR and UV spectroscopy of cold (10 K) gas-phase ions, we probe the inherent conformational preferences of the $^{D}$P and $^{L}$P diastereomers in the protonated peptide [YAPAA+H]$^{+}$, where only intramolecular interactions are possible. Consistent with the solution phase studies, one of the conformers of [YADPAA+H]$^{+}$ is folded into a charge-stabilized $beta$-hairpin turn. However, a second predominant conformer family containing two sequential $gamma$-turns is also identified, with similar energetic stability. A single conformational isomer of the $^{L}$P diastereomer, [YALPAA+H]$^{+}$, is found and assigned to a structure that is not the anticipated “mirror image” $beta$-turn. Instead, the $^{L}$P stereo center promotes a cis alanine-proline amide bond. The assigned structures contain clues that the preference of the $^{D}$P diastereomer to support a trans-amide bond and the proclivity of $^{L}$P for a cis-amide bond is sterically driven and can be reversed by substituting glycine for alanine in position 2, forming [YGLPAA+H]$^{+}$. These results provide a basis for understanding the residue-specific and stereo-specific alterations in the potential energy surface that underlie these changing preferences, providing insights to the origin of $beta$-hairpin formation.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Permalink
http://hdl.handle.net/2142/97149
DOI
https://doi.org/10.15278/isms.2017.FE04
Copyright and License Information
Copyright 2017 Andrew F. DeBlase

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Abstracts & Presentations - 2017 International Symposium on Molecular Spectroscopy PRIMARY