Related Experiment Video
Updated: Aug 14, 2025

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy
Published on: October 9, 2020
Assignment of aromatic side-chain spins and characterization of their distance restraints at fast MAS
Sahil Ahlawat1, Subbarao Mohana Venkata Mopidevi1, Pravin P Taware1
1Tata Institute of Fundamental Research Hyderabad, Sy. No. 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500 046, India.
Abstract:
The assignment of aromatic side-chain spins has always been more challenging than assigning backbone and aliphatic spins. Selective labeling combined with mutagenesis has been the approach for assigning aromatic spins. This manuscript reports a method for assigning aromatic spins in a fully protonated protein by connecting them to the backbone atoms using a low-power TOBSY sequence. The pulse sequence employs residual polarization and sequential acquisitions techniques to record HN- and HC-detected spectra in a single experiment. The unambiguous assignment of aromatic spins also enables the characterization of 1H-1H distance restraints involving aromatic spins. Broadband (RFDR) and selective (BASS-SD) recoupling sequences were used to generate HN-ΗC, HC-HN and HC-HC restraints involving the side-chain proton spins of aromatic residues. This approach has been demonstrated on a fully protonated U-[13C,15N] labeled GB1 sample at 95-100 kHz MAS.
More Related Videos
Related Concept Videos
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
NMR Spectroscopy: Spin–Spin Coupling
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
Spin–Spin Coupling Constant: Overview
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...

