ALPHA-HELICAL VERSUS 3(10)-HELICAL CONFORMATION of ALANINE-BASED PEPTIDES in AQUEOUS-SOLUTION - AN ELECTRON-SPIN-RESONANCE INVESTIGATION

ALPHA-HELICAL VERSUS 3(10)-HELICAL CONFORMATION of ALANINE-BASED PEPTIDES in AQUEOUS-SOLUTION - AN ELECTRON-SPIN-RESONANCE INVESTIGATION

Autor Smythe, M. L. Google Scholar
Nakaie, C. R. Google Scholar
Marshall, G. R. Google Scholar
Instituição WASHINGTON UNIV
Universidade Federal de São Paulo (UNIFESP)
UNIV QUEENSLAND
Resumo 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.
Idioma Inglês
Data de publicação 1995-10-25
Publicado em Journal of the American Chemical Society. Washington: Amer Chemical Soc, v. 117, n. 42, p. 10555-10562, 1995.
ISSN 0002-7863 (Sherpa/Romeo, fator de impacto)
Publicador Amer Chemical Soc
Extensão 10555-10562
Fonte http://dx.doi.org/10.1021/ja00147a018
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:A1995TC32600018
Endereço permanente http://repositorio.unifesp.br/handle/11600/25533

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