Measuring And Modeling Highly Accurate 15N Chemical Shift Tensors In A Peptide.

Keywords

15 N; chemical shift tensor; DFT; peptide; solid-state NMR

Abstract

NMR studies measuring chemical shift tensors are increasingly being employed to assign structure in difficult-to-crystallize solids. For small organic molecules, such studies usually focus on 13C sites, but proteins and peptides are more commonly described using 15N amide sites. An important and often neglected consideration when measuring shift tensors is the evaluation of their accuracy against benchmark standards, where available. Here we measure 15N tensors in the dipeptide glycylglycine at natural abundance using the slow-spinning FIREMAT method with SPINAL-64 decoupling. The accuracy of these 15N tensors is evaluated by comparing to benchmark single crystal NMR 15N measurements and found to be statistically indistinguishable. These FIREMAT experimental results are further used to evaluate the accuracy of theoretical predictions of tensors from four different density functional theory (DFT) methods that include lattice effects. The best theoretical approach provides a root mean square (rms) difference of ±3.9 ppm and is obtained from a fragment-based method and the PBE0 density functional.

Publication Date

8-18-2017

Publication Title

ChemPhysChem

Volume

18

Issue

16

Number of Pages

2225-2232

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1002/cphc.201700357

Socpus ID

85020987132 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85020987132

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