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

Go Back   BioNMR > Educational resources > NMR Questions and Answers
Advanced Search



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  
Unread 09-13-2005, 02:08 PM
Junior Member
 
Join Date: Sep 2005
Posts: 1
Points: 12, Level: 1
Points: 12, Level: 1 Points: 12, Level: 1 Points: 12, Level: 1
Level up: 23%, 38 Points needed
Level up: 23% Level up: 23% Level up: 23%
Activity: 0%
Activity: 0% Activity: 0% Activity: 0%
NMR Credits: 0
NMR Points: 12
Downloads: 0
Uploads: 0
Default Answered: Chemistry question on NMR Spectroscopy?

What exactly does "proton shielding", chemical shifts and exterior magnetic field in respect to NMR mean? What are the trends in the chemical shift? Is it the higher the shift, the lower the proton shielding, thus it is easier for them to "flip", or is it the other way around? And what does "resonance" mean?Thanks for your inspiring explanations, which I understood fairly well.
Reply With Quote


Did you find this post helpful? Yes | No
Best Answer - Posted by Aaron H
Proton "shielding" is when the positive charge of the proton is "shielded" (less prominent) by the electron cloud. When you have a molecule that includes electronegative atoms, such as Oxygen or halides, the electrons will spend more time closer to the electronegative atoms and less near their respective protons. So the "H" in "OH" will be less shielded than the H's in CH4. Deshielding moves the signal a bit to the left -- so when you're consulting your reference chart -- if it says "3.2", you won't want to rule out signals that show up a little above that (3.5-4.0).Resonance is the property of certain molecular structures that involve the sharing of a double bond. The archetypal example is a Benzene Ring (or an "Aromatic Ring") which is a C6H6 cyclohexane molecule with conjugated (alternating) double bonding. When the electrons in a double bond could just as easily be in an identical location elsewhere in the molecule, they'll jump around. For example:H3C-O=C-O-CH3In this diester, it is symmetrical and although the double-bond is currently on the left side, the electrons will alternate between that arrangement and this one.H3C-O-C=O-CH3

Content provided by Yahoo Answers.

  #2  
Unread 09-13-2005, 02:08 PM
Junior Member
 
Join Date: Sep 2005
Posts: 1
Points: 2, Level: 1
Points: 2, Level: 1 Points: 2, Level: 1 Points: 2, Level: 1
Level up: 3%, 48 Points needed
Level up: 3% Level up: 3% Level up: 3%
Activity: 0%
Activity: 0% Activity: 0% Activity: 0%
NMR Credits: 100
NMR Points: 2
Downloads: 0
Uploads: 0
Provided Answers: 1
Default Chemistry question on NMR Spectroscopy?

Proton "shielding" is when the positive charge of the proton is "shielded" (less prominent) by the electron cloud. When you have a molecule that includes electronegative atoms, such as Oxygen or halides, the electrons will spend more time closer to the electronegative atoms and less near their respective protons. So the "H" in "OH" will be less shielded than the H's in CH4. Deshielding moves the signal a bit to the left -- so when you're consulting your reference chart -- if it says "3.2", you won't want to rule out signals that show up a little above that (3.5-4.0).Resonance is the property of certain molecular structures that involve the sharing of a double bond. The archetypal example is a Benzene Ring (or an "Aromatic Ring") which is a C6H6 cyclohexane molecule with conjugated (alternating) double bonding. When the electrons in a double bond could just as easily be in an identical location elsewhere in the molecule, they'll jump around. For example:H3C-O=C-O-CH3In this diester, it is symmetrical and although the double-bond is currently on the left side, the electrons will alternate between that arrangement and this one.H3C-O-C=O-CH3

Content provided by Yahoo Answers.
Reply With Quote


1 out of 1 members found this post helpful. Did you find this post helpful? Yes | No
Reply
Similar Threads
Thread Thread Starter Forum Replies Last Post
[NMR tweet] Nuclear Magnetic Resonance Spectroscopy in Environmental Chemistry (Topics in Environmental Chemistry): http://amzn.to/hcCYg0
Nuclear Magnetic Resonance Spectroscopy in Environmental Chemistry (Topics in Environmental Chemistry): http://amzn.to/hcCYg0 Published by Desireeskh (Desiree Odonovan) on 2011-04-16T20:03:42Z Source: Twitter
nmrlearner Twitter NMR 0 04-16-2011 08:13 PM
[NMR tweet] http://www.pulist.net/introduction-to-organic-spectroscopy-oxford-chemistry-primers.html #magnetic #resonance #spectroscopy #nuclear Int
http://www.pulist.net/introduction-to-organic-spectroscopy-oxford-chemistry-primers.html #magnetic #resonance #spectroscopy #nuclear Int Published by puwisdom (James chain) on 2011-01-28T05:26:08Z Source: Twitter
nmrlearner Twitter NMR 0 01-28-2011 06:01 AM
[NMR tweet] Organic Chemistry H Nuclear Magnetic Resonance Question!? http://www.mritechnicianprograms.com/?p=183
Organic Chemistry H Nuclear Magnetic Resonance Question!? http://www.mritechnicianprograms.com/?p=183 Published by radiologyschool (radiology schools) on 2011-01-18T01:15:07Z Source: Twitter
nmrlearner Twitter NMR 0 01-18-2011 01:22 AM
Application of NMR Spectroscopy in Medicinal Chemistry and Drug Discovery.
Application of NMR Spectroscopy in Medicinal Chemistry and Drug Discovery. Related Articles Application of NMR Spectroscopy in Medicinal Chemistry and Drug Discovery. Curr Top Med Chem. 2010 Sep 2; Authors: Ohno A, Inomata K, Tochio H, Shirakawa M "In-cell nuclear magnetic resonance (NMR)" is a unique method for characterization of conformation, interaction and dynamics of proteins inside living cells at atomic level. Since the method was proposed by Dötch and co-workers in 2001 , its application had been limited to bacterial cells and...
nmrlearner Journal club 0 09-03-2010 02:30 PM
A question about NMR spectroscopy delta?
How do I find the delta for hydrogens? For example, a peak is between 7 and 8. How do I find the exact chemical shift delta?I searched everywhere on how to calculate it but I don't get the same delta of 7.39.
Bobby NMR Questions and Answers 2 08-15-2005 03:38 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

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 On
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 10:30 PM.


Map