High resolution crystal structures have established the distortion of the peptide bond's planarity. We are cross-correlating high resolution (less than 1Å) structures from the RSCB Protein Data Bank (PDB) and the Biological Magnetic Resonance Bank (BMRB). The dependence of backbone atom chemical shifts on peptide backbone dihedral angles Φ and Ψ has been described by others. It is possible that the out-of-plane peptide bond torsion angle (ω) exerts further influence on these chemical shifts. Thus this work may improve the accuracy of chemical shift-based protein structure determination.