Correlation between 15N NMR chemical shifts in proteins and secondary structure.
An empirical correlation between the peptide 15N chemical shift, delta 15Ni, and the backbone torsion angles phi i, psi i-1 is reported. By using two-dimensional shielding surfaces delta (phi i, psi i-1), it is possible in many cases to make reasonably accurate predictions of 15N chemical shifts for a given structure. On average, the rms error between experiment and prediction is about 3.5 ppm. Results for threonine, valine and isoleucine are worse (approximately 4.8 ppm), due presumably to chi 1-distribution/gamma-gauche effects. The rms errors for the other amino acids are approximately 3 ppm, for a typical maximal chemical shift range of approximately 15-20 ppm. Thus, there is a significant correlation between 15N chemical shift and secondary structure.
Department of Chemistry, University of Illinois at Urbana-Champaign 61801.
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D000596:Amino Acids; D016208:Databases, Factual; D004798:Enzymes / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008433:Mathematics; D009587:Nitrogen Isotopes; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*
D000596:Amino Acids; D004798:Enzymes; D009587:Nitrogen Isotopes; D011506:Proteins