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Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
How Does an Amide-N Chemical Shift Tensor Vary in Peptides?
Alan Poon1, Jeff Birn, A Ramamoorthy
1Biophysics Research Division, Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055.
The Journal of Physical Chemistry. B
|May 2, 2008
Summary
This study reveals how amide nitrogen-15 chemical shift anisotropy (CSA) tensors vary in peptides. Hydrogen bonding and local sequence significantly influence CSA, aiding future protein NMR studies.
Area of Science:
- Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
- Computational Chemistry
- Structural Biology
Background:
- The amide nitrogen-15 chemical shift anisotropy (CSA) tensor is crucial for understanding peptide and protein structure.
- Existing literature lacks systematic data on how the amide-(15)N CSA tensor varies across different peptide sequences and conformations.
Purpose of the Study:
- To systematically investigate the variations in the amide-(15)N CSA tensor for various peptides.
- To elucidate the factors influencing these tensor variations, including peptide sequence, conformation, and hydrogen bonding.
Main Methods:
- Quantum chemical calculations were employed to determine amide-(15)N CSA tensors.
- Calculations were performed on dipeptides, and model Ala-X and X-Ala sequences in both α-helical and β-sheet conformations.
Main Results:
- Significant variations in amide-(15)N CSA tensor principal values were observed in both isolated and extended peptide structures.
- Hydrogen bonding interactions at the carbonyl and N-H groups demonstrably affect the CSA tensor.
- The amide-(15)N CSA tensor is influenced by atoms within a five-bond distance, indicating local sequence dependence.
Conclusions:
- The amide-(15)N CSA tensor is primarily influenced by adjacent residues, suggesting its relevance within a tripeptide context.
- This tensor can potentially be extrapolated for a specific residue within a tripeptide sequence across different polypeptides or proteins, provided similar conformational and environmental conditions.
- Findings facilitate more accurate interpretation of NMR structural data for proteins.
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