Journal article

Publication year: 2007

Pages: 1568-1577

Journal: Journal of the American Chemical Society

Volume number: 129

Issue number: 6

ISSN: 0002-7863

DOI Link: https://doi.org/10.1021/ja065461k

Publisher: American Chemical Society

Abstract: 

Complete nuclear magnetic resonance (NMR) chemical-shielding tensors, σ,
have been computed at different levels of density-functional theory
(DFT), within the gauge-including atomic orbital (GIAO) formalism, for
the atoms of the peptide model For-L-Ala-NH₂ as a function of the backbone dihedral angles φ and ψ by employing a dense grid of 10°. A complete set of rigorously orthogonal symmetric tensor invariants, {σ_iso, ρ, τ}, is introduced, where σ_iso is the usual isotropic chemical shielding, while the newly introduced ρ and τ parameters describe the magnitude and the orientation/shape of the chemical-shielding anisotropy (CSA), respectively. The set {σ_iso, ρ, τ}
is unaffected by unitary transformations of the symmetric part of the
shielding tensor. The mathematically and physically motivated {ρ, τ} anisotropy pair is easily connected to more traditional shielding anisotropy measures, like span (Ω) and skew (κ).
The effectiveness of the different partitions of the CSA information in
predicting conformations of peptides and proteins has been tested
throughout the Ramachandran space by generating theoretical NMR
anisotropy surfaces for our For-L-Ala-NH₂ model. The CSA surfaces, including Ω(φ, ψ), κ(φ,
ψ), ρ(φ, ψ), and τ(φ, ψ) are highly structured. Individually, none of
these surfaces is able to distinguish unequivocally between the α-helix and β-strand secondary structural types of proteins. However, two- and three-dimensional correlated plots, including Ω versus κ, ρ versus τ, and σ_iso versus ρ versus τ, especially for ¹³C^α, have considerable promise in distinguishing among all four of the major secondary structural elements.

Harvard Citation style: Czinki, E., Csaszar, A., Magyarfalvi, G., Schreiner, P. and Allen, W. (2007) Secondary Structures of Peptides and Proteins via NMR Chemical-Shielding Anisotropy (CSA) Parameters, Journal of the American Chemical Society, 129(6), pp. 1568-1577. https://doi.org/10.1021/ja065461k

APA Citation style: Czinki, E., Csaszar, A., Magyarfalvi, G., Schreiner, P., & Allen, W. (2007). Secondary Structures of Peptides and Proteins via NMR Chemical-Shielding Anisotropy (CSA) Parameters. Journal of the American Chemical Society. 129(6), 1568-1577. https://doi.org/10.1021/ja065461k