Orientation of Amide-Nitrogen-15 Chemical Shift Tensors in Peptides: A Quantum Chemical Study Export

@article{citeulike:4305995, abstract = {Knowledge of the orientation of the nitrogen-15 chemical shift anisotropy (CSA) tensor is critical for a variety of experiments that provide information on protein structure and dynamics in the solid and solution states. Unfortunately, the methods available for determining the orientation of the CSA tensor experimentally have inherent limitations. Rotation studies of a single crystal provide complete information but are tedious and limited in applicability. Solid-state NMR studies on powder samples can be applied to a greater range of samples but suffer from ambiguities in the results obtained. Density functional gauge-including-atomic-orbitals (GIAO) calculations of the orientations of 15N CSA tensors in peptides are presented here as an independent source of confirmation for these studies. A comparison of the calculated 15N CSA orientations with the available experimental values from single-crystal and powder studies shows excellent agreement after a partial, constrained optimization of some of the crystal structures used in the calculation. The results from this study suggest that the orientation as well as the magnitudes of 15N CSA tensors may vary from molecule to molecule. The calculated alphaN angle varies from 0o to 24o with the majority in the 10o to 20o range and the betaN angle varies from 17o to 24o in good agreement with most of the solid-state NMR experimental results. Hydrogen bonding is shown to have negligible effect on the orientation of 15N CSA tensor in accordance with recent theoretical predictions. Furthermore, it is demonstrated that the orientation of the 15N CSA can be calculated accurately with much smaller basis sets than is needed to calculate the chemical shift, suggesting that the routine application of ab initio calculations to the determination of 15N CSA tensor orientations in large biomolecules might be possible.}, author = {Brender, Jeffrey R. and Taylor, Deanne M. and Ramamoorthy, A.}, citeulike-article-id = {4305995}, citeulike-linkout-0 = {http://dx.doi.org/10.1021/ja001980q}, citeulike-linkout-1 = {http://pubs.acs.org/doi/abs/10.1021/ja001980q}, day = {1}, doi = {10.1021/ja001980q}, journal = {Journal of the American Chemical Society}, keywords = {15n, ab-initio, csa, nmr}, month = {February}, number = {5}, pages = {914--922}, posted-at = {2009-04-14 05:53:25}, priority = {4}, title = {Orientation of Amide-Nitrogen-15 Chemical Shift Tensors in Peptides: A Quantum Chemical Study}, url = {http://dx.doi.org/10.1021/ja001980q}, volume = {123}, year = {2001} }

TY - JOUR ID - citeulike:4305995 L3 - citeulike-article-id:4305995 N2 - Knowledge of the orientation of the nitrogen-15 chemical shift anisotropy (CSA) tensor is critical for a variety of experiments that provide information on protein structure and dynamics in the solid and solution states. Unfortunately, the methods available for determining the orientation of the CSA tensor experimentally have inherent limitations. Rotation studies of a single crystal provide complete information but are tedious and limited in applicability. Solid-state NMR studies on powder samples can be applied to a greater range of samples but suffer from ambiguities in the results obtained. Density functional gauge-including-atomic-orbitals (GIAO) calculations of the orientations of 15N CSA tensors in peptides are presented here as an independent source of confirmation for these studies. A comparison of the calculated 15N CSA orientations with the available experimental values from single-crystal and powder studies shows excellent agreement after a partial, constrained optimization of some of the crystal structures used in the calculation. The results from this study suggest that the orientation as well as the magnitudes of 15N CSA tensors may vary from molecule to molecule. The calculated alphaN angle varies from 0o to 24o with the majority in the 10o to 20o range and the betaN angle varies from 17o to 24o in good agreement with most of the solid-state NMR experimental results. Hydrogen bonding is shown to have negligible effect on the orientation of 15N CSA tensor in accordance with recent theoretical predictions. Furthermore, it is demonstrated that the orientation of the 15N CSA can be calculated accurately with much smaller basis sets than is needed to calculate the chemical shift, suggesting that the routine application of ab initio calculations to the determination of 15N CSA tensor orientations in large biomolecules might be possible. IS - 5 JF - Journal of the American Chemical Society EP - 922 TI - Orientation of Amide-Nitrogen-15 Chemical Shift Tensors in Peptides: A Quantum Chemical Study VL - 123 SP - 914 KW - 15n KW - ab-initio KW - csa KW - nmr AU - Brender, Jeffrey AU - Taylor, Deanne AU - Ramamoorthy, A PY - 2001/02/01/ UR - http://dx.doi.org/10.1021/ja001980q ER -