BioNMR
NMR aggregator & online community since 2003
BioNMR    
Learn or help to learn NMR - get free NMR books!
 

Go Back   BioNMR > NMR community > News from NMR blogs
Advanced Search
Home Forums Wiki NMR feeds Downloads Register Today's Posts



Jobs Groups Conferences Literature Pulse sequences Software forums Programs Sample preps Web resources BioNMR issues


Webservers
NMR processing:
MDD
NMR assignment:
Backbone:
Autoassign
MARS
UNIO Match
PINE
Side-chains:
UNIO ATNOS-Ascan
NOEs:
UNIO ATNOS-Candid
UNIO Candid
ASDP
Structure from NMR restraints:
Ab initio:
GeNMR
Cyana
XPLOR-NIH
ASDP
UNIO ATNOS-Candid
UNIO Candid
Fragment-based:
BMRB CS-Rosetta
Rosetta-NMR (Robetta)
Template-based:
GeNMR
I-TASSER
Refinement:
Amber
Structure from chemical shifts:
Fragment-based:
WeNMR CS-Rosetta
BMRB CS-Rosetta
Homology-based:
CS23D
Simshift
Torsion angles from chemical shifts:
Preditor
TALOS
Promega- Proline
Secondary structure from chemical shifts:
CSI (via RCI server)
TALOS
MICS caps, β-turns
d2D
PECAN
Flexibility from chemical shifts:
RCI
Interactions from chemical shifts:
HADDOCK
Chemical shifts re-referencing:
Shiftcor
UNIO Shiftinspector
LACS
CheckShift
RefDB
NMR model quality:
NOEs, other restraints:
PROSESS
PSVS
RPF scores
iCing
Chemical shifts:
PROSESS
CheShift2
Vasco
iCing
RDCs:
DC
Anisofit
Pseudocontact shifts:
Anisofit
Protein geomtery:
Resolution-by-Proxy
PROSESS
What-If
iCing
PSVS
MolProbity
SAVES2 or SAVES4
Vadar
Prosa
ProQ
MetaMQAPII
PSQS
Eval123D
STAN
Ramachandran Plot
Rampage
ERRAT
Verify_3D
Harmony
Quality Control Check
NMR spectrum prediction:
FANDAS
MestReS
V-NMR
Flexibility from structure:
Backbone S2
Methyl S2
B-factor
Molecular dynamics:
Gromacs
Amber
Antechamber
Chemical shifts prediction:
From structure:
Shiftx2
Sparta+
Camshift
CH3shift- Methyl
ArShift- Aromatic
ShiftS
Proshift
PPM
CheShift-2- Cα
From sequence:
Shifty
Camcoil
Poulsen_rc_CS
Disordered proteins:
MAXOCC
Format conversion & validation:
CCPN
From NMR-STAR 3.1
Validate NMR-STAR 3.1
NMR sample preparation:
Protein disorder:
DisMeta
Protein solubility:
camLILA
ccSOL
Camfold
camGroEL
Zyggregator
Isotope labeling:
UPLABEL
Solid-state NMR:
sedNMR


Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
  #1  
Old 12-15-2014, 03:18 AM
nmrlearner's Avatar
Senior Member
 
Join Date: Jan 2005
Posts: 23,777
Points: 193,617, Level: 100
Points: 193,617, Level: 100 Points: 193,617, Level: 100 Points: 193,617, Level: 100
Level up: 0%, 0 Points needed
Level up: 0% Level up: 0% Level up: 0%
Activity: 50.7%
Activity: 50.7% Activity: 50.7% Activity: 50.7%
Last Achievements
Award-Showcase
NMR Credits: 0
NMR Points: 193,617
Downloads: 0
Uploads: 0
Default Quadruplet, triplet … so simple?

Quadruplet, triplet … so simple?

In the picture below I’m showing the ‘synthetic’ NMR spectrum of Ethanol. It has been synthesized using Mnova Spin Simulation capabilities and the experimental values (chemical shifts and couplings) taken from the NMR spectrum of ethanol recorded at 600 MHz in water, so the OH signal will not show up.








Nothing new under the sun. This is a very simple spectrum where the two observed multiplets seem to follow very nicely the well-known first order multiplet rules that most chemists use on daily basis. In this case, a very simple A3X2 spin system.
But does this mean that this spectrum is actually composed by only 7 peaks? The answer is, of course not, there are many more peaks! But because of the very limited resolution, most of them are not observed and merge in such a way that only 7 peaks are ultimately observed.
In other words, the number of NMR transitionsis usually much larger than the number of peaks we actually observe in the spectrum. Just to give an example: A molecule containing 30 coupled protons will result in a spectrum having 16106127360 (=1.61E+10) transitions. As its corresponding NMR spectrum will show only about 100-200 peaks, that makes it well over eighty million quantum transitions per resolved peak!



For example, let’s magnify the quadruplet and use Mnova unique capabilities to display the individual transitions by simply hovering with the mouse cursor over the atoms in the molecule (CH2 in this case). We can see that there are some ‘hidden peaks’, these are the NMR transitions calculated by diagonalizing the NMR Hamiltonian.


These transitions are so close that they cannot be resolved under the usual NMR resolution conditions. In fact, to separate all these signals, it would be necessary to have a spectral resolution of


Whilst this is far from being feasible experimentally nowadays, it is easy to do numerically. In the figure below I’m displaying the same synthetic spectrum of Ethanol but this time synthesized using a line width of just 0.01 Hz and 1 MB of digital data points. Now the individual transitions can be seen as resolved peaks so in this example a transition will be virtually equivalent to an NMR peak.







Simply put, an NMR spectrum is just a superposition of all spectral transitions (which can be in the order of millions), transitions compose peaks, peaks group into multiplets, and multiplets compose the spectrum.


The ability of Mnova to show the individual NMR transitions in a synthetic spectrum can be a good teaching tool


For a more theoretical and rigorous discussion on NMR transitions, see A.D. Bain, D.A. Fletcher and P. Hazendonk. "What is a transition?" Concepts in Magnetic Resonance 10 85- 98 (1998) (link)





More...

Source: NMR-analysis blog
Reply With Quote


Did you find this post helpful? Yes | No

Reply
Similar Threads
Thread Thread Starter Forum Replies Last Post
[Question from NMRWiki Q&A forum] simple stddiff parameters
simple stddiff parameters Hi, I'm working on a bruker avance 400 spectrometer and using topspin version 1.3 software. I want to get a std-nmr (saturation transfer difference nmr) spectrum. This is the first time for me to set up and processes a STD nmr experiment. I'm trying to use simplest pulse programme "stddiff" from brukers pulse programme catalogue. Could anyone help me abuot basic parameter settings (at least neccessary ones) for this experiment. For example I'm confused about "dimensions" of this püse programme. Because according to the pulse programme catalogue "stddiff" is a one...
nmrlearner News from other NMR forums 0 07-09-2014 03:37 AM
Dynamic nuclear polarization with photoexcited triplet electrons in a glassy matrix
From The DNP-NMR Blog: Dynamic nuclear polarization with photoexcited triplet electrons in a glassy matrix Tateishi, K., et al., Dynamic nuclear polarization with photoexcited triplet electrons in a glassy matrix. Angew Chem Int Ed Engl, 2013. 52(50): p. 13307-10. http://www.ncbi.nlm.nih.gov/pubmed/24249595
nmrlearner News from NMR blogs 0 04-25-2014 10:26 PM
An apparatus for pulsed ESR and DNP experiments using optically excited triplet states down to liquid helium temperatures
From The DNP-NMR Blog: An apparatus for pulsed ESR and DNP experiments using optically excited triplet states down to liquid helium temperatures Eichhorn, T.R., et al., An apparatus for pulsed ESR and DNP experiments using optically excited triplet states down to liquid helium temperatures. J. Magn. Reson., 2013. 234(0): p. 58-66. http://dx.doi.org/10.1016/j.jmr.2013.06.009
nmrlearner News from NMR blogs 0 08-30-2013 04:35 PM
[Question from NMRWiki Q&A forum] Simple 1H-NMR Assignment Query
Simple 1H-NMR Assignment Query Hi guys, sorry to be really cheeky and sign up simply to ask for help, but here goes. I've done a simple Grignard addition of isopropyl magnesium bromide to 3-methoxy benzaldehyde and I'm just assigning the peaks, but I've come up stumped on one issue. Concerning the isopropyl -CH(CH3)2 proton (at approximately d=1.95p.p.m.), it's observed as a septet, but the integration is 2.14 and I'm stuck as to why. This Grignard addition should occur non-preferentially at either the Re-/Si- face of the aldehyde, so can it be explained by some form of entiomeric...
nmrlearner News from other NMR forums 0 10-15-2011 08:16 PM
[Stan NMR blog] The Geometry and some General Characteristics of the Isotropic AB Quadruplet
The Geometry and some General Characteristics of the Isotropic AB Quadruplet An NMR essay opening a new series entitled "Know Thy Spins". More...
nmrlearner News from NMR blogs 0 08-21-2010 06:14 PM
[Stan NMR blog] RSS (Really Simple Syndication) for Dummies
RSS (Really Simple Syndication) for Dummies Educational article which explains how easy it is to make your site an RSS news channel. More...
nmrlearner News from NMR blogs 0 08-21-2010 06:14 PM
[Stan NMR blog] Geometry of the AB quadruplet
Geometry of the AB quadruplet This is the opening article of a series entitled 'Know Thy Spins'. More...
nmrlearner News from NMR blogs 0 08-21-2010 05:42 PM



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



BioNMR advertisements to pay for website hosting and domain registration. Nobody does it for us.



Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright, BioNMR.com, 2003-2013
Search Engine Friendly URLs by vBSEO 3.6.0

All times are GMT. The time now is 10:21 AM.


Map