Related Experiment Video
Updated: Jul 16, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Reconstructing NMR spectra of "invisible" excited protein states using HSQC and HMQC experiments
Nikolai R Skrynnikov1, Frederick W Dahlquist, Lewis E Kay
1Protein Engineering Network Center of Excellence, Department of Medical Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8. nikolai@purdue.edu
Abstract:
Carr-Purcell-Meiboom-Gill (CPMG) relaxation measurements employing trains of 180 degrees pulses with variable pulse spacing provide valuable information about systems undergoing millisecond-time-scale chemical exchange. Fits of the CPMG relaxation dispersion profiles yield rates of interconversion, relative populations, and absolute values of chemical shift differences between the exchanging states, |Deltaomega|. It is shown that the sign of Deltaomega that is lacking from CPMG dispersion experiments can be obtained from a comparison of chemical shifts in the indirect dimensions in either a pair of HSQC (heteronuclear single quantum coherence) spectra recorded at different magnetic fields or HSQC and HMQC (heteronuclear multiple quantum coherence) spectra obtained at a single field. The methodology is illustrated with an application to a cavity mutant of T4 lysozyme in which a leucine at position 99 has been replaced by an alanine, giving rise to exchange between ground state and excited state conformations with a rate on the order of 1450 s(-1) at 25 degrees C.
Related Concept Videos
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 slanted or...
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
¹³C NMR: ¹H–¹³C Decoupling
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
2D NMR: Overview of Homonuclear Correlation Techniques
COSY90 is the standard two-dimensional (2D) COSY experiment that...
2D NMR: Overview of Heteronuclear Correlation Techniques

