If one has an NMR spectrometer with hardware capable of synthesizing and amplifying the frequency of 19F from the 1H channel and a broadband NMR probe whose 1H channel can tune down to 19F, then one is able to do 19F - 13C HMQC experiments. The figure below shows an example of a 19F - 13C HMQC spectrum collected on a Bruker AVANCE 500 NMR spectrometer using a 5 mm broadband probe. The fluorine spectrum is plotted on the top and the 13C[19F] spectrum is plotted on the side. The panel on the left shows the spectrum optimized for one-bond coupling, while that on the right shows the spectrum optimized for two-bond coupling. Note that the protonated carbons are doublets as proton decoupling is not possible in this configuration. The large signal, off scale in the 13C[19F] spectrum is due to the solvent (benzene-d6).
Two-dimensional concurrent HMQC-COSY as an approach for small molecule chemical shift assignment and compound identification
Two-dimensional concurrent HMQC-COSY as an approach for small molecule chemical shift assignment and compound identification
Abstract Chemical shift assignment is the first step toward the structure elucidation of natural products and other chemical compounds. We propose here the use of 2D concurrent HMQC-COSY as an experiment for rapid chemical shift assignment of small molecules. This experiment provides well-dispersed 1Hâ??13C peak patterns that are distinctive for different functional groups plus 1Hâ??1H COSY connectivities that serve to identify adjacent groups. The COSY diagonal...
nmrlearner
Journal club
0
03-09-2011 04:19 AM
[NMR paper] Reconstructing NMR spectra of "invisible" excited protein states using HSQC and HMQC
Reconstructing NMR spectra of "invisible" excited protein states using HSQC and HMQC experiments.
Related Articles Reconstructing NMR spectra of "invisible" excited protein states using HSQC and HMQC experiments.
J Am Chem Soc. 2002 Oct 16;124(41):12352-60
Authors: Skrynnikov NR, Dahlquist FW, Kay LE
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...
nmrlearner
Journal club
0
11-24-2010 08:58 PM
15N SOFAST-HMQC to study fast H-D exchange
Very Fast Two-Dimensional NMR Spectroscopy for Real-Time Investigation of Dynamic Events in Proteins on the Time Scale of Seconds
Paul Schanda and Bernhard Brutscher
J. Am. Chem. Soc.; 2005; 127(22) pp 8014 - 8015
http://pubs.acs.org/isubscribe/journals/jacsat/127/i22/figures/ja051306en00001.gif
Abstract:
We demonstrate for different protein samples that 2D 1H-15N correlation NMR spectra can be recorded in a few seconds of acquisition time using a new band-selective optimized flip-angle short-transient heteronuclear multiple quantum coherence experiment. This has enabled us to...
19f - 13c hmqc
Linear Mode
