Related Articles14N NMR relaxation times of several protein amino acids in aqueous solution--comparison with 17O NMR data and estimation of the relative hydration numbers in the cationic and zwitterionic forms.
J Magn Reson. 2003 Oct;164(2):294-303
Authors: Troganis AN, Tsanaktsidis C, Gerothanassis IP
The 14N nuclear magnetic resonance (NMR) linewidths of the alpha-amino groups of several protein amino acids were measured in aqueous solution, with and without composite proton decoupling, to estimate the effect of proton exchange and molecular weight on the linewidths. It is shown that, contrary to earlier claims, the increase in the linewidth at low pH is not exclusively due to the effect of proton exchange broadening. The 14N linewidths, under composite proton decoupling, increase with the bulk of the amino acid, and increase at low pH. Statistical treatment of the experimental 14N and literature 17O NMR data was performed assuming two models: (i) an isotropic molecular reorientation of a rigid sphere in a medium of viscosity eta, (ii) a stochastic diffusion of the amino and carboxyl groups comprising contributions from internal (tauint) and overall (taumol) motions. Assuming a single correlation time from overall molecular reorientation (taumol), then, a linear correlation was found between the linewidths and the molecular weights of the protein amino acids at the pH values 0.5 and 6.0, which are characteristic of the cationic and zwitterionic forms, respectively. The slopes of the straight-lines were found to be dependent of pH for 14N, contrary to the 17O linear correlations whose slopes were found to be independent of pH. Assuming effective correlation times of the amino and carboxyl groups, which comprise contributions from the internal (tauint) and overall (taumol) motions, then, a significant improvement of the statistics of the regression analysis was observed. The 14N relaxation data, in conjunction with 17O NMR linewidths, can be interpreted by assuming that the 14N quadrupole coupling constants (NQCCs) are influenced by the protonation state of the carboxyl group, the 17O NQCCs remain constant, and the cationic form of the amino acids is hydrated by an excess of 1-3 molecules of water relative to the zwitterionic state.
[Question from NMRWiki Q&A forum] 13C quaternary centers in amino acids
13C quaternary centers in amino acids
I've got a sample of about 5mg of an amino acid that is the final product of a a synthesis. Due to the long relaxation time that the carboxylic and the alpha C we only got a 200 varian Mercury instrument and we're unable to obtain those signals. I was wondering if an APT is better than DEPT, because we're only interested in this signals and i've heard the overall pulse sequence is shorter than the DEPT, increasing the number of scans in the same period of time.
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nmrlearner
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09-01-2011 07:20 AM
[Question from NMRWiki Q&A forum] 13C cuaternary centers in amino acids
13C cuaternary centers in amino acids
I've got a sample of about 5mg of an amino acid that is the final product of a a synthesis. Due to the long relaxation time that the carboxilic and the alpha C we only got a 200 varian Mercury instrument and we're unable to obtain those signals. I was wondering if an APT is better than DEPT, because we're only interested in this signals and i've heart the overall pulse sequence is shorter than the DEPT, increasing the number of scans in the same period of time
Check if somebody has answered this question on NMRWiki QA forum
nmrlearner
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08-31-2011 07:12 PM
[KPWU blog] Names of Atoms of Amino acids
Names of Atoms of Amino acids
I really hate the inconsistent nomenclature of atoms of amino acids between different programs/database. I finished all NOESY assignment on Sparky using PDB nomenclature and the Sparky XPLOR constraint plugin (shortcut xf) doesn’t take care of the differences between XPLOR and PDB. Thus I have to find a table showing me the differences of names http://stats.wordpress.com/b.gif?host=kpwu.wordpress.com&blog=76132&post=262&subd=kpwu&ref=&feed=1
Go to KPWU blog to read complete post.
nmrlearner
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01-28-2011 04:52 AM
[NMR paper] Effective rotational correlation times of proteins from NMR relaxation interference.
Effective rotational correlation times of proteins from NMR relaxation interference.
Related Articles Effective rotational correlation times of proteins from NMR relaxation interference.
J Magn Reson. 2006 Jan;178(1):72-6
Authors: Lee D, Hilty C, Wider G, Wüthrich K
Knowledge of the effective rotational correlation times, tauc, for the modulation of anisotropic spin-spin interactions in macromolecules subject to Brownian motion in solution is of key interest for the practice of NMR spectroscopy in structural biology. The value of tauc enables...
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12-01-2010 06:56 PM
[NMR paper] Study of the behaviour of amino acids in aqueous solution by time-domain NMR and high
Study of the behaviour of amino acids in aqueous solution by time-domain NMR and high-resolution NMR.
Related Articles Study of the behaviour of amino acids in aqueous solution by time-domain NMR and high-resolution NMR.
Magn Reson Chem. 2005 Apr;43(4):309-15
Authors: Khallouk M, Rutledge DN, Silva AM, Delgadillo I
The study of protein hydration by time-domain NMR is complicated by the great number of interactions involved, resulting from the presence of several amino acids and the possible modifications produced by the various structures....
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11-25-2010 08:21 PM
[NMR paper] Relaxation of water protons in highly concentrated aqueous protein systems studied by
Relaxation of water protons in highly concentrated aqueous protein systems studied by 1H NMR spectroscopy.
Related Articles Relaxation of water protons in highly concentrated aqueous protein systems studied by 1H NMR spectroscopy.
Z Naturforsch C. 2001 Nov-Dec;56(11-12):1075-81
Authors: Szuminska K, Gutsze A, Kowalczyk A
Concentrated Aqueous Protein Systems, Proton Relaxation Times, Slow Chemical Exchange In this paper we present proton spin-lattice (T1) and spin-spin (T2) relaxation times measured vs. concentration, temperature, pulse...
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11-19-2010 08:44 PM
[NMR paper] The solution conformations of amino acids from molecular dynamics simulations of Gly-
The solution conformations of amino acids from molecular dynamics simulations of Gly-X-Gly peptides: comparison with NMR parameters.
Related Articles The solution conformations of amino acids from molecular dynamics simulations of Gly-X-Gly peptides: comparison with NMR parameters.
Biochem Cell Biol. 1998;76(2-3):164-70
Authors: van der Spoel D
The conformations that amino acids can adopt in the random coil state are of fundamental interest in the context of protein folding research and studies of protein-peptide interactions. To date, no...
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11-17-2010 11:06 PM
[NMR paper] Comparison between the phi distribution of the amino acids in the protein database an
Comparison between the phi distribution of the amino acids in the protein database and NMR data indicates that amino acids have various phi propensities in the random coil conformation.
http://www.ncbi.nlm.nih.gov/corehtml/query/egifs/http:--linkinghub.elsevier.com-ihub-images-PubMedLink.gif Related Articles Comparison between the phi distribution of the amino acids in the protein database and NMR data indicates that amino acids have various phi propensities in the random coil conformation.
J Mol Biol. 1995 Nov 24;254(2):322-33
Authors: Serrano L
...