Abstract A shift of the water proton precession frequency is described that can introduce errors in chemical shifts derived using the water signal as the chemical shift reference. This shift, fs, arises as a consequence of radiation damping when the water proton and detector circuit resonance frequencies differ. Herein it is shown that experimental values of fs, measured as a function of detector circuit tuning offset for 500 and 900 MHz cryogenic probes, are in good agreement with theory. Of importance is the fact that even a small degree of mistuning, which does not significantly impact the performance of a pulse sequence, introduces chemical shift errors of ±0.03 ppm, that negatively impact many types of experiments. A simple remedy that attenuates the frequency shift is presented.
Content Type Journal Article
Pages 241-244
DOI 10.1007/s10858-009-9363-6
Authors
Dennis A. Torchia, National Institutes of Health National Institute of Dental and Craniofacial Research Bethesda MD 20892-4307 USA
[Question from NMRWiki Q&A forum] Tuning probe failed after a dual probe was replaced with a BBI probe
Tuning probe failed after a dual probe was replaced with a BBI probe
We generally use Dual to run 13C and BBI to run 2D. After changed the probe, the command "edhead" was used to set the probe. Put the sample tube, lock the solvent, and then type "atma" to tune the probe. We always do it like this, but now we can not tune the proton after installed the BBI probe (13C is OK). The dip can not be found by "atma", and "atmm" was also not work on forming a dip. What is the most possible reason for this error? How to solve it and avoid it in the future ? Thanks. (Instrument: Bruker 400 MHz,...
nmrlearner
News from other NMR forums
0
08-23-2011 05:31 PM
Cryogenic temperature effects and resolution upon slow cooling of protein preparations in solid state NMR
Cryogenic temperature effects and resolution upon slow cooling of protein preparations in solid state NMR
Abstract X-ray crystallography using synchrotron radiation and the technique of dynamic nuclear polarization (DNP) in nuclear magnetic resonance (NMR) require samples to be kept at temperatures below 100 K. Protein dynamics are poorly understood below the freezing point of water and down to liquid nitrogen temperatures. Therefore, we investigate the α-spectrin SH3 domain by magic angle spinning (MAS) solid state NMR (ssNMR) at various temperatures while cooling slowly. Cooling down...
nmrlearner
Journal club
0
08-13-2011 02:47 AM
Cryogenic temperature effects and resolution upon slow cooling of protein preparations in solid state NMR.
Cryogenic temperature effects and resolution upon slow cooling of protein preparations in solid state NMR.
Cryogenic temperature effects and resolution upon slow cooling of protein preparations in solid state NMR.
J Biomol NMR. 2011 Aug 9;
Authors: Linden AH, Franks WT, Akbey U, Lange S, van Rossum BJ, Oschkinat H
X-ray crystallography using synchrotron radiation and the technique of dynamic nuclear polarization (DNP) in nuclear magnetic resonance (NMR) require samples to be kept at temperatures below 100*K. Protein dynamics are poorly understood...
nmrlearner
Journal club
0
08-10-2011 12:30 PM
SHIFTX2: significantly improved protein chemical shift prediction
SHIFTX2: significantly improved protein chemical shift prediction
Abstract A new computer program, called SHIFTX2, is described which is capable of rapidly and accurately calculating diamagnetic 1H, 13C and 15N chemical shifts from protein coordinate data. Compared to its predecessor (SHIFTX) and to other existing protein chemical shift prediction programs, SHIFTX2 is substantially more accurate (up to 26% better by correlation coefficient with an RMS error that is up to 3.3Ã? smaller) than the next best performing program. It also provides significantly more coverage (up to 10% more),...
nmrlearner
Journal club
0
04-01-2011 09:31 PM
Introductory NMR & MRI: Video 01: Precession and Resonance
Introductory NMR & MRI: Video 01: Precession and Resonance
http://i.ytimg.com/vi/7aRKAXD4dAg/default.jpg
Introductory NMR & MRI: Video 01: Precession and Resonance
Paul Callaghan gives an introduction to NMR and MRI. Paul uses a mechanical wheel to illustrate the key concepts of precession, relaxation, and resonance. First in a 10 episode series produced by Magritek Ltd. see www.magritek.com for more
From: magritek
Views: 26368
http://gdata.youtube.com/static/images/icn_star_full_11x11.gif http://gdata.youtube.com/static/images/icn_star_full_11x11.gif...
Slight mistuning of a cryogenic probe significantly perturbs the water 1H precession frequency
Linear Mode
