An official website of the United States government
The structure and spectroscopic properties of the amide bond are a topic of fundamental interest in chemistry and biology. Herein, we report 17 O NMR and 15 N NMR spectroscopic data for four series of sterically-hindered acyclic amides. Despite the utility of 17 O NMR and 15 N NMR spectroscopy, these methods are severely underutilized in the experimental determination of electronic properties of the amide bond. The data demonstrate that a combined use of 17 O NMR and 15 N NMR serves as a powerful tool in assessing electronic effects of the amide bond substitution as a measure of electrophilicity of the amide bond. Notably, we demonstrate that steric destabilization of the amide bond results in electronically-activated amides that are comparable in terms of electrophilicity to acyl fluorides and carboxylic acid anhydrides.
more »
« less
Inquiring 199 Hg NMR Parameters by Combining Ab Initio Molecular Dynamics and Relativistic NMR Calculations
- Award ID(s):
- 2152633
- PAR ID:
- 10507930
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- Inorganic Chemistry
- Volume:
- 63
- Issue:
- 4
- ISSN:
- 0020-1669
- Page Range / eLocation ID:
- 2082 to 2089
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract In oriented‐sample (OS) solid‐state NMR of membrane proteins, the angular‐dependent dipolar couplings and chemical shifts provide a direct input for structure calculations. However, so far only1H–15N dipolar couplings and15N chemical shifts have been routinely assessed in oriented15N‐labeled samples. The main obstacle for extending this technique to membrane proteins of arbitrary topology has remained in the lack of additional experimental restraints. We have developed a new experimental triple‐resonance NMR technique, which was applied to uniformly doubly (15N,13C)‐labeled Pf1 coat protein in magnetically aligned DMPC/DHPC bicelles. The previously inaccessible1Hα–13Cαdipolar couplings have been measured, which make it possible to determine the torsion angles between the peptide planes without assuming α‐helical structure a priori. The fitting of three angular restraints per peptide plane and filtering by Rosetta scoring functions has yielded a consensus α‐helical transmembrane structure for Pf1 protein.more » « less
-
Abstract Cannabicitran is an important cannabinoid natural product produced byCannabis sativaand is often found at surprisingly high levels (up to ~10%) in “purified” commercial cannabidiol (CBD) extract preparations. Despite the prevalence of this molecule in CBD oil and other cannabinoid‐related products, and the rapidly expanding interest in cannabinoids for treatment of a wide range of physiological conditions, only unassigned1H NMR data and partial unambiguous13C assignments have been published. Herein, we report the complete1H and13C NMR assignments of cannabicitran and comparatively evaluate the performance of several density functional theory (DFT) methods with varying levels of theory for the calculation of NMR chemical shifts.more » « less
-
An NMR supersequence is introduced for the rapid acquisition of 15 N-CEST and methyl- 13 C-CEST experiments in the same pulse sequence for applications to proteins. The high sensitivity and accuracy allows the simultaneous quantitative characterization of backbone and side-chain dynamics on the millisecond timescale ideal for routine screening for alternative protein states.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.inorgchem.3c03878
