Journal of Biomolecular NMR

, Volume 5, Issue 1, pp 14–24

‘Random coil’ 1H chemical shifts obtained as a function of temperature and trifluoroethanol concentration for the peptide series GGXGG

Authors

  • Gene Merutka
    • Department of Molecular BiologyThe Scripps Research Institute
  • H. Jane Dyson
    • Department of Molecular BiologyThe Scripps Research Institute
  • Peter E. Wright
    • Department of Molecular BiologyThe Scripps Research Institute
Research Paper

DOI: 10.1007/BF00227466

Cite this article as:
Merutka, G., Jane Dyson, H. & Wright, P.E. J Biomol NMR (1995) 5: 14. doi:10.1007/BF00227466

Summary

Proton chemical shifts of a series of disordered linear peptides (H-Gly-Gly-X-Gly-Gly-OH, with X being one of the 20 naturally occurring amino acids) have been obtained using 1D and 2D 1H NMR at pH 5.0 as a function of temperature and solvent composition. The use of 2D methods has allowed some ambiguities in side-chain assignments in previous studies to be resolved. An additional benefit of the temperature data is that they can be used to obtain ‘random coil’ amide proton chemical shifts at any temperature between 278 and 318 K by interpolation. Changes of chemical shift as a function of trifluoroethanol concentration have also been determined at a variety of temperatures for a subset of peptides. Significant changes are found in backbone and side-chain amide proton chemical shifts in these ‘random coil’ peptides with increasing amounts of trifluoroethanol, suggesting that caution is required when interpreting chemical shift changes as a measure of helix formation in peptides in the presence of this solvent. Comparison of the proton chemical shifts obtained here for H-Gly-Gly-X-Gly-Gly-OH with those for H-Gly-Gly-X-Ala-OH [Bundi, A. and Wüthrich, K. (1979) Biopolymers, 18, 285–297] and for Ac-Gly-Gly-X-Ala-Gly-Gly-NH2 [Wishart, D.S., Bigam, C.G., Holm, A., Hodges, R.S. and Sykes, B.D. (1995) J. Biomol. NMR, 5, 67–81] generally shows good agreement for CH protons, but reveals significant variability for NH protons. Amide proton chemical shifts appear to be highly sensitive to local sequence variations and probably also to solution conditions. Caution must therefore be exercised in any structural interpretation based on amide proton chemical shifts.

Keywords

‘Random coil’ chemical shiftsTemperature coefficientTrifluoroethanolPeptide proton chemical shifts
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Copyright information

© ESCOM Science Publishers B.V. 1995