Le H, Oldfield E
Department of Chemistry, University of Illinois at Urbana-Champaign 61801.
J Biomol NMR. 1994 May;4(3):341-8. doi: 10.1007/BF00179345.
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.
报道了肽的15N化学位移δ15Ni与主链扭转角φi、ψi-1之间的经验相关性。通过使用二维屏蔽表面δ(φi, ψi-1)，在许多情况下可以对给定结构的15N化学位移做出合理准确的预测。平均而言，实验值与预测值之间的均方根误差约为3.5 ppm。苏氨酸、缬氨酸和异亮氨酸的结果较差（约4.8 ppm），这可能是由于χ1分布/γ-gauche效应。对于其他氨基酸，在典型的最大化学位移范围约为15 - 20 ppm时，均方根误差约为3 ppm。因此，15N化学位移与二级结构之间存在显著相关性。
