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UV Raman demonstrates that α-helical polyalanine peptides melt to polyproline II conformations

Asher, SA and Mikhonin, AV and Bykov, S (2004) UV Raman demonstrates that α-helical polyalanine peptides melt to polyproline II conformations. Journal of the American Chemical Society, 126 (27). 8433 - 8440. ISSN 0002-7863

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We examined the 204-nm UV Raman spectra of the peptide XAO, which was previously found by Shi et al.'s NMR study to occur in aqueous solution in a polyproline II (PPII) conformation (Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 9190). The UV Raman spectra of XAO are essentially identical to the spectra of small peptides such as ala5 and to the large 21 -residue predominantly Ala peptide, AP. We conclude that the non-α-helical conformations of these peptides are dominantly PPII. Thus, AP, which is highly α-helical at room temperature, melts to a PPII conformation. There is no indication of any population of intermediate disordered conformations. We continued our development of methods to relate the Ramachandran ψ-angle to the amide III band frequency. We describe a new method to estimate the Ramachandran ψ-angular distributions from amide III band line shapes measured in 204-nm UV Raman spectra. We used this method to compare the ψ-distributions in XAO, ala5, the non-α-helical state of AP, and acid-denatured apomyoglobin. In addition, we estimated the ψ-angle distributions of peptide bonds which occur in non-α-helix and non-β-sheet conformations in a small library of proteins.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Asher, SAasher@pitt.eduASHER
Mikhonin, AV
Bykov, S
Date: 14 July 2004
Date Type: Publication
Journal or Publication Title: Journal of the American Chemical Society
Volume: 126
Number: 27
Page Range: 8433 - 8440
DOI or Unique Handle: 10.1021/ja049518j
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 0002-7863
MeSH Headings: Amides--chemistry; Chemistry, Physical; Peptides--chemistry; Physicochemical Phenomena; Protein Conformation; Protein Structure, Secondary; Spectrophotometry, Ultraviolet; Spectrum Analysis, Raman--methods; Temperature
PubMed ID: 15238000
Date Deposited: 08 Feb 2013 21:21
Last Modified: 22 Jun 2021 13:55


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