How uniform is the peptide plane geometry? A high-accuracy NMR study of dipolar C(?)-C'/H (N)-N cross-correlated relaxation.
How uniform is the peptide plane geometry? A high-accuracy NMR study of dipolar C(?)-C'/H (N)-N cross-correlated relaxation.
J Biomol NMR. 2011 Jun 3;
Authors: Vögeli B
Highly precise and accurate measurements of very small NMR cross-correlated relaxation rates, namely those between protein H (i) (N) -N(i) and C (i-1) (?) -C(i-1)' dipoles, are demonstrated with an error of 0.03*s(-1) for GB3. Because the projection angles between the two dipole vectors are very close to the magic angle the rates range only from -0.2 to +0.2*s(-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 C'-N bonds and/or pyramidalization of the nitrogen atoms. A clear alternating pattern along the sequence is observed in ? strands 1, 3 and 4 of GB3, where the side chains of almost all residues with large positive rates are solvent exposed. In the ? 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 ? strand 3, but not in the loops and the two central strands of the sheet for which no alternating pattern is predicted.
PMID: 21638015 [PubMed - as supplied by publisher]
Source:
PubMed