α-Helical versus 310-Helical Conformation of Alanine-Based Peptides in Aqueous Solution: An Electron Spin Resonance Investigation

Smythe M.L., Nakaie C.R. and Marshall G.R. (1995) α-Helical versus 310-Helical Conformation of Alanine-Based Peptides in Aqueous Solution: An Electron Spin Resonance Investigation. Journal of the American Chemical Society, 117 42: 10555-10562. doi:10.1021/ja00147a018


Author Smythe M.L.
Nakaie C.R.
Marshall G.R.
Title α-Helical versus 310-Helical Conformation of Alanine-Based Peptides in Aqueous Solution: An Electron Spin Resonance Investigation
Journal name Journal of the American Chemical Society   Check publisher's open access policy
ISSN 1520-5126
Publication date 1995-01-01
Year available 1995
Sub-type Article (original research)
DOI 10.1021/ja00147a018
Open Access Status Not yet assessed
Volume 117
Issue 42
Start page 10555
End page 10562
Total pages 8
Place of publication WASHINGTON
Publisher AMER CHEMICAL SOC
Language eng
Abstract Due to the difficulties in experimentally differentiating between the alpha- and 3(10)-helical conformations in solution, isolated helical peptides have been assumed to be in the alpha-helical conformation. However, recent electron spin resonance (ESR) studies have suggested that such peptides, in particular short alanine-based peptides, are 3(10)-helical (Miick, S. M.; et al. Nature 1992, 359, 653-5). This result prompted us to further investigate the helical conformations of alanine-based peptides in solution using electron spin resonance spectroscopy. Unlike previous investigations with a flexible link connecting the spin-label to the peptide backbone, we used a conformationally constrained spin-label (4-amino-4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl, Toac) that is rigidly attached to the peptide backbone. From a combination of molecular modeling and ESR spectroscopy investigations, it was concluded that these alanine-based peptides exist primarily in the alpha-helical conformation, and not the 3(10)-form as previously suggested for an analogous set of peptides in aqueous environments. This discrepancy is thought to be due to the differences in flexibility of the spin-labels employed. The conformationally constrained spin-label Toac used in this study should accurately reflect the backbone conformation. Free energy surfaces, or potentials of mean force, for the conformational transition of the spin-label used in previous studies (Miick S. M.; et al. Nature 1992, 359, 653-5) suggest that this spin-label is too flexible to accurately distinguish between the alpha- and 3(10)-helical conformations.
Keyword Alpha,alpha-Dialkyl Amino-Acids
Aminoisobutyric-Acid
Molecular-Dynamics
Oligopeptides Rich
Ribonuclease-A
Chain-Length
Transition
Simulations
Proteins
Polypeptides
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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