How uniform is the peptide plane geometry? A high-accuracy NMR study of dipolar Cαâ??Câ?²/HNâ??N cross-correlated relaxation

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How uniform is the peptide plane geometry? A high-accuracy NMR study of dipolar Cαâ??Câ?²/HNâ??N cross-correlated relaxation


Abstract Highly precise and accurate measurements of very small NMR cross-correlated relaxation rates, namely those between protein HiNâ??Ni and Ciâ??1αâ??Ciâ??1â?² dipoles, are demonstrated with an error of 0.03 sâ??1 for GB3. Because the projection angles between the two dipole vectors are very close to the magic angle the rates range only from â??0.2 to +0.2 sâ??1. Small changes of the average vector orientations have a dramatic impact on the relative values. The rates suggest deviation from idealized peptide plane geometry caused by twists around the Câ?²â??N bonds and/or pyramidalization of the nitrogen atoms. A clear alternating pattern along the sequence is observed in β strands 1, 3 and 4 of GB3, where the side chains of almost all residues with large positive rates are solvent exposed. In the α helix all rates are relatively large and positive. Some of the currently most accurate structures of GB3 determined by both high resolution X-ray crystallography and NMR are in satisfactory agreement with the experimental rates in the helix and β strand 3, but not in the loops and the two central strands of the sheet for which no alternating pattern is predicted.

• Content Type Journal Article
• Pages 1-15
• DOI 10.1007/s10858-011-9519-z
• Authors
  • Beat Vögeli, Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, ETH-Hönggerberg, 8093 Zürich, Switzerland

• • Journal Journal of Biomolecular NMR
  • Online ISSN 1573-5001
  • Print ISSN 0925-2738

Source: Journal of Biomolecular NMR