Local helix content in an alanine-rich peptide as determined by the complete set of 3JHNα coupling constants |
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Authors: | Glenn L Millhauser Chris J Stenland Kimberly A Bolin Frank J M van de Ven |
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Institution: | (1) Department of Chemistry and Biochemistry, University of California, 95064 Santa Cruz, CA, USA;(2) Biophysical Chemistry Laboratory, Nijmegen SON Research Center, University of Nijmegen, NL-6525 ED Nijmegen, The Netherlands |
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Abstract: | Summary Alanine-rich peptides serve as models for exploring the factors that control helix structure in peptides and proteins. Scalar CH-NH couplings (3JHN) are an extremely useful measure of local helix content; however, the large alanine content in these peptides leads to significant signal overlap in the CH region of 1H 2D NMR spectra. Quantitative determination of all possible 3JHN values is, therefore, very challenging. Szyperski and co-workers (1992) J. Magn. Reson., 99, 552–560] have recently developed a method for determining 3JHN from NOESY spectra. Because 3JHN may be determined from 2D peaks outside of the CH region, there is a much greater likelihood of identifying resolved resonances and measuring the associated coupling constants. It is demonstrated here that 3JHN can be obtained for every residue in the helical peptide Ac-(AAAAK)3A-NH2. The resulting 3JHN profile clearly identifies a helical structure in the middle of the peptide and further suggests that the respective helix termini unfold via distinct pathways.Abbreviations
3JHN
three-bond CH-NH scalar coupling constant
- NOE
nuclear Overhauser enhancement
- NOESY
two-dimensional nuclear Overhauser spectroscopy
- COSY
two-dimensional correlated spectroscopy
- DQF-COSY
two-dimensional double-quantum-filtered correlated spectroscopy
- TOCSY
two-dimensional total correlation spectroscopy
To whom correspondence should be addressed.Deceased March 5, 1996. |
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Keywords: | J coupling Coupling constants Inverse fitting Alanine Helix Peptide |
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