There are many different NMR techniques used to probe molecular structure. Two very useful methods are the HSQC (or HMQC) sequence used to obtain heteronuclear coupling correlations and the TOCSY sequence used to look at extended homonuclear coupling correlations. These are among the most widely used pulse sequences by chemists to help elucidate the molecular structure of organic molecules. The sequences can also be combined into a single HSQC-TOCSY sequence which is simply an HSQC followed by a TOCSY spin lock. For the case of 1H and 13C in organic molecules, the HSQC-TOCSY spectrum provides 1H TOCSY subspectra of the isolated spin systems in the rows at each of the 13C frequencies. Overlap of 1H resonances which may have appeared in a simple 1H TOCSY spectrum can be resolved in the HSQC-TOCSY spectrum provided there is enough shift dispersion in the 13C spectrum. An example of this is shown in the figure below. The top panel shows the HSQC-TOCSY spectrum for 3-heptanone collected on a 300 MHz instrument. One can see the two spin systems on either side of the carbonyl group, color coded in yellow and pink. The second panel shows an expansion of the region within the red square of the first panel. Here we can separate the overlapping quartet and triplet for the methylene protons on either side of the carbonyl group.
[Question from NMRWiki Q&A forum] HSQC perturbation
HSQC perturbation
Dear All,
I am trying to determine the interaction between 2 proteins. Is there any reference or literature which report the determination of binding constant between 2 proteins in which intensity drop of HSQC cross peaks can be used as the measuring parameter. As when I titrate these 2 proteins only change which I observe is intensity drop. I tried other biophysical techniques to determine binding constant, but results are not satisfactory.
Any suggestion would be useful
Regards
nmrlearner
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09-24-2013 02:18 AM
[NMRpipe Yahoo group] Re: N15 separated NOESY and TOCSY
Re: N15 separated NOESY and TOCSY
Thank you for your replies. The processing script of TOCSY (NH plane): $NMRTXT/ext.xz.com fid/test%03d.fid xz001.fid nmrPipe -in xz001.fid \ ... -out xzf.ft2
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05-29-2011 11:00 AM
[NMRpipe Yahoo group] Re: N15 separated NOESY and TOCSY
Re: N15 separated NOESY and TOCSY
Hi Iris, Another question is what do you mean by the NH vs HH planes in regards to the 3D matrix (a single 3D peak can't be positive viewed along one axis and
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05-27-2011 10:40 AM
[NMRpipe Yahoo group] Re: N15 separated NOESY and TOCSY
Re: N15 separated NOESY and TOCSY
Hi Iris, It's difficult to diagnose the problem without seeing the processing script, but what phase correction was used in the 15N dimension? If the initial
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05-26-2011 10:34 PM
[NMRpipe Yahoo group] N15 separated NOESY and TOCSY
N15 separated NOESY and TOCSY
Hello, I did a N15 separated TOCSY experiment and used the following script: #!/bin/csh bruk2pipe -in ./ser \ -bad 0.0 -aswap -DMX -decim 2632 -dspfvs 20
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05-26-2011 10:34 PM
[Question from NMRWiki Q&A forum] HCCH-Tocsy connectivities
HCCH-Tocsy connectivities
What I see from this picture (linked from www.protein-nmr.org.uk):
http://www.protein-nmr.org.uk/pictures/experiment_types/hcch_tocsy.png
that shows an HCCH-TOCSY magnetisation transfer I do not see any transfer from HD to HB, but in my peaks I see a peak that seems it can be connected az Leu CB-HB2-HD22Can I have these peaks in HCCH-TOCSY?
would you please introduce me a reference that tell me what kind of connection can be visible in HC(C)H-Tocsy
nmrlearner
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11-17-2010 06:08 PM
[Nature network NMR forum] HCCH-TOCSY (0 replies)
HCCH-TOCSY (0 replies)
Hello everybody,
I am a biologist who has jumped into NMR :(
I hope this is an active forum so that I can improve myself and can help someday to others.
I have a very stupid question!!! Do you know if I can see some HN peaks correlated with C-beta in HCCH-TOCSY?
Cheers,