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Title: Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn

Abstract

Incorporation of the unnatural D-proline ( DP) stereoisomer into a polypeptide sequence is a typical strategy to encourage formation of β-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 DP and LP diastereomers in the protonated peptide [YAPAA+H] +, where only intramolecular interactions are possible. Consistent with the solution-phase studies, one of the conformers of [YA DPAA+H] + is folded into a charge-stabilized β-hairpin turn. However, a second predominant conformer family containing two sequential γ-turns is also identified, with similar energetic stability. A single conformational isomer of the LP diastereomer, [YA LPAA+H] +, is found and assigned to a structure that is not the anticipated “mirror image” β-turn. Instead, the LP stereocenter promotes a cis-alanine–proline amide bond. The assigned structures contain clues that the preference of the DP diastereomer to support a trans-amide bond and the proclivity of LP for a cis-amide bond is sterically driven and can be reversed by substituting glycine for alanine in position 2, forming [YG LPAA+H] +. These results provide a basis for understanding the residue-specific and stereospecific alterations in the potential energy surfacemore » that underlie these changing preferences, providing insights to the origin of β-hairpin formation.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry
Publication Date:
Research Org.:
Purdue Univ., West Lafayette, IN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1349951
Alternate Identifier(s):
OSTI ID: 1352565
Grant/Contract Number:  
FG02-00ER15105; CHE-1465028
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 15; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

DeBlase, Andrew F., Harrilal, Christopher P., Lawler, John T., Burke, Nicole L., McLuckey, Scott A., and Zwier, Timothy S. Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn. United States: N. p., 2017. Web. doi:10.1021/jacs.7b01315.
DeBlase, Andrew F., Harrilal, Christopher P., Lawler, John T., Burke, Nicole L., McLuckey, Scott A., & Zwier, Timothy S. Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn. United States. doi:10.1021/jacs.7b01315.
DeBlase, Andrew F., Harrilal, Christopher P., Lawler, John T., Burke, Nicole L., McLuckey, Scott A., and Zwier, Timothy S. Wed . "Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn". United States. doi:10.1021/jacs.7b01315.
@article{osti_1349951,
title = {Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn},
author = {DeBlase, Andrew F. and Harrilal, Christopher P. and Lawler, John T. and Burke, Nicole L. and McLuckey, Scott A. and Zwier, Timothy S.},
abstractNote = {Incorporation of the unnatural D-proline (DP) stereoisomer into a polypeptide sequence is a typical strategy to encourage formation of β-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 DP and LP 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 β-hairpin turn. However, a second predominant conformer family containing two sequential γ-turns is also identified, with similar energetic stability. A single conformational isomer of the LP diastereomer, [YALPAA+H]+, is found and assigned to a structure that is not the anticipated “mirror image” β-turn. Instead, the LP stereocenter promotes a cis-alanine–proline amide bond. The assigned structures contain clues that the preference of the DP diastereomer to support a trans-amide bond and the proclivity of LP 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 stereospecific alterations in the potential energy surface that underlie these changing preferences, providing insights to the origin of β-hairpin formation.},
doi = {10.1021/jacs.7b01315},
journal = {Journal of the American Chemical Society},
number = 15,
volume = 139,
place = {United States},
year = {Wed Mar 29 00:00:00 EDT 2017},
month = {Wed Mar 29 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1021/jacs.7b01315

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Cited by: 3 works
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