Related ArticlesThe nearest-neighbor effect on random-coil NMR chemical shifts demonstrated using a low-complexity amino-acid sequence.
Protein Pept Lett. 2016 Sep 20;
Authors: Chen TC, Hsiao CL, Huang SJ, Huang JR
Abstract
In NMR experiments, the chemical shift is typically the first parameter measured and is a source of structural information for biomolecules. Indeed, secondary chemical shifts, the difference between the measured chemical shifts and those expected for a randomly oriented sequence of peptides (the "random coil"), are correlated with the secondary structure of proteins; secondary shift analysis is thereby a standard approach in structural biology. For intrinsically disordered or denatured proteins furthermore, secondary chemical shifts reveal the propensity of particular segments to form different secondary structures. However, because the atoms in unfolded proteins all have very similar chemical environments, the chemical shifts measured for a certain atom type vary less than in globular proteins. Since chemical shifts can be measured precisely, the secondary chemical shifts calculated for an unfolded system depend mainly on the particular random coil chemical shift database chosen as a point of reference. Certain databases correct the random coil shift for a given residue based on its neighbors in the amino acid sequence. However, these corrections are typically derived from the analysis of model peptides; there have been relatively few direct and systematic studies of the effect of neighboring residues for specific amino acid sequences in disordered proteins. For the study reported here, we used the intrinsically disordered C-terminal domain of TDP-43, which has a highly repetitive amino-acid sequence, as a model system. We assigned the chemical shifts of this protein at low pH in urea. Our results demonstrate that the identity of the nearest neighbors is decisive in determining the value of the chemical shift for atoms in a random coil arrangement. Based on these observations, we also outline a possible approach to construct a random-coil library of chemical shifts that comprises all possible arrangement of tripeptides from a manageable number of polypeptides.
PMID: 27653629 [PubMed - as supplied by publisher]
pH-dependent random coil 1H, 13C, and 15N chemical shifts of the ionizable amino acids: a guide for protein pK a measurements
pH-dependent random coil 1H, 13C, and 15N chemical shifts of the ionizable amino acids: a guide for protein pK a measurements
Abstract
The pK a values and charge states of ionizable residues in polypeptides and proteins are frequently determined via NMR-monitored pH titrations. To aid the interpretation of the resulting titration data, we have measured the pH-dependent chemical shifts of nearly all the 1H, 13C, and 15N nuclei in the seven common ionizable amino acids (XÂ*=Â*Asp, Glu, His, Cys, Tyr, Lys, and Arg)...
nmrlearner
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09-20-2014 05:45 AM
RCI - Random Coil Index for predicting protein flexibility from chemical shifts
RCI website
RCI method predicts protein flexibility by calculating the Random Coil Index from backbone chemical shifts and predicting values of model-free order parameters as well as per-residue RMSF of NMR and MD ensembles from the Random Coil Index.
The key advantages of this protocol over existing methods of studying protein flexibility are (i) it does not require prior knowledge of a protein's tertiary structure, (ii) it is not sensitive to the protein's overall tumbling and (iii) it does not require additional NMR measurements beyond the standard experiments for backbone...
markber
NMR software
0
02-02-2012 11:36 PM
Sequence correction of random coil chemical shifts: correlation between neighbor correction factors and changes in the Ramachandran distribution
Sequence correction of random coil chemical shifts: correlation between neighbor correction factors and changes in the Ramachandran distribution
Abstract Random coil chemical shifts are necessary for secondary chemical shift analysis, which is the main NMR method for identification of secondary structure in proteins. One of the largest challenges in the determination of random coil chemical shifts is accounting for the effect of neighboring residues. The contributions from the neighboring residues are typically removed by using neighbor correction factors determined based on each...
nmrlearner
Journal club
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06-06-2011 12:53 AM
Random coil chemical shift for intrinsically disordered proteins: effects of temperature and pH
Random coil chemical shift for intrinsically disordered proteins: effects of temperature and pH
Abstract Secondary chemical shift analysis is the main NMR method for detection of transiently formed secondary structure in intrinsically disordered proteins. The quality of the secondary chemical shifts is dependent on an appropriate choice of random coil chemical shifts. We report random coil chemical shifts and sequence correction factors determined for a GGXGG peptide series following the approach of Schwarzinger et al. (J Am Chem Soc 123(13):2970â??2978, 2001). The chemical shifts are...
nmrlearner
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01-17-2011 02:40 AM
[NMR paper] Proline-directed random-coil chemical shift values as a tool for the NMR assignment o
Proline-directed random-coil chemical shift values as a tool for the NMR assignment of the tau phosphorylation sites.
Related Articles Proline-directed random-coil chemical shift values as a tool for the NMR assignment of the tau phosphorylation sites.
Chembiochem. 2004 Jan 3;5(1):73-8
Authors: Lippens G, Wieruszeski JM, Leroy A, Smet C, Sillen A, Buée L, Landrieu I
NMR spectroscopy of the full-length neuronal Tau protein has proved to be difficult due to the length of the protein and the unfavorable amino acid composition. We show that the...
nmrlearner
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11-24-2010 09:25 PM
[NMR paper] Sequence-dependent correction of random coil NMR chemical shifts.
Sequence-dependent correction of random coil NMR chemical shifts.
Related Articles Sequence-dependent correction of random coil NMR chemical shifts.
J Am Chem Soc. 2001 Apr 4;123(13):2970-8
Authors: Schwarzinger S, Kroon GJ, Foss TR, Chung J, Wright PE, Dyson HJ
Random coil chemical shifts are commonly used to detect secondary structure elements in proteins in chemical shift index calculations. While this technique is very reliable for folded proteins, application to unfolded proteins reveals significant deviations from measured random coil...
nmrlearner
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11-19-2010 08:32 PM
Sequential nearest-neighbor effects on computed 13Cα chemical shifts
Abstract To evaluate sequential nearest-neighbor effects on quantum-chemical calculations of 13Cα chemical shifts, we selected the structure of the nucleic acid binding (NAB) protein from the SARS coronavirus determined by NMR in solution (PDB id 2K87). NAB is a 116-residue α/β protein, which contains 9 prolines and has 50% of its residues located in loops and turns. Overall, the results presented here show that sizeable nearest-neighbor effects are seen only for residues preceding proline, where Pro introduces an overestimation, on average, of 1.73 ppm in the computed 13Cα chemical...
nmrlearner
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08-14-2010 04:19 AM
Chemical shift prediction in random coil peptides
Please check this program and let me know if it does work for your random coil peptides.
http://bloch.anu.edu.au/cgi-bin/shiftpred/shiftpred.cgi
Thank you,
Bogdan Bancia
bbancia@yahoo.com