Density functional calculations of backbone N-15 shielding tensors in beta-sheet and turn residues of protein G

作者：Cai Ling; Kosov Daniel S; Fushman David^*

来源：Journal of Biomolecular NMR, 2011, 50(1): 19-33.

DOI：10.1007/s10858-011-9474-8

• Nitrogen-15 shielding tensor
• Ab initio calculation
• Density-functional calculation
• Beta-sheet
• Turns
• Protein G

We performed density functional calculations of backbone N-15 shielding tensors in the regions of beta-sheet and turns of protein G. The calculations were carried out for all twenty-four beta-sheet residues and eight beta-turn residues in the protein GB3 and the results were compared with the available experimental data from solid-state and solution NMR measurements. Together with the alpha-helix data, our calculations cover 39 out of the 55 residues (or 71%) in GB3. The applicability of several computational models developed previously (Cai et al. in J Biomol NMR 45:245-253, 2009) to compute N-15 shielding tensors of alpha-helical residues is assessed. We show that the proposed quantum chemical computational model is capable of predicting isotropic N-15 chemical shifts for an entire protein that are in good correlation with experimental data. However, the individual components of the predicted N-15 shielding tensor agree with experiment less well: the computed values show much larger spread than the experimental data, and there is a profound difference in the behavior of the tensor components for alpha-helix/turns and beta-sheet residues. We discuss possible reasons for this.

• 出版日期2011-5