The predictive accuracy of secondary chemical shifts is more affected by protein seco
Abstract Biomolecular NMR spectroscopy frequently employs estimates of protein secondary structure using secondary chemical shift (Î?δ) values, measured as the difference between experimental and random coil chemical shifts (RCCS). Most published random coil data have been determined in aqueous conditions, reasonable for non-membrane proteins, but potentially less relevant for membrane proteins. Two new RCCS sets are presented here, determined in dimethyl sulfoxide (DMSO) and chloroform:methanol:water (4:4:1 by volume) at 298 K. A web-based program, CS-CHEMeleon, has been implemented to determine the accuracy of secondary structure assessment by calculating and comparing Î?δ values for various RCCS datasets. Using CS-CHEMeleon, Î?δ predicted versus experimentally determined secondary structures were compared for large datasets of membrane and non-membrane proteins as a function of RCCS dataset, Î?δ threshold, nucleus, localized parameter averaging and secondary structure type. Optimized Î?δ thresholds are presented both for published and for the DMSO and chloroform:methanol:water derived RCCS tables. Despite obvious RCCS variations between datasets, prediction of secondary structure was consistently similar. Strikingly, predictive accuracy seems to be most dependent upon the type of secondary structure, with helices being the most accurately predicted by Î?δ values using five different RCCS tables. We suggest caution when using Î?δ-based restraints in structure calculations as the underlying dataset may be biased. Comparative assessment of multiple RCCS datasets should be performed, and resulting Î?δ-based restraints weighted appropriately relative to other experimental restraints.
Content Type Journal Article
DOI 10.1007/s10858-010-9400-5
Authors
Marie-Laurence Tremblay, Dalhousie University Department of Biochemistry & Molecular Biology Halifax NS B3H 1X5 Canada
Aaron W. Banks, Dalhousie University Department of Biochemistry & Molecular Biology Halifax NS B3H 1X5 Canada
Jan K. Rainey, Dalhousie University Department of Biochemistry & Molecular Biology Halifax NS B3H 1X5 Canada
VITAL NMR: using chemical shift derived secondary structure information for a limited set of amino acids to assess homology model accuracy
VITAL NMR: using chemical shift derived secondary structure information for a limited set of amino acids to assess homology model accuracy
Abstract Homology modeling is a powerful tool for predicting protein structures, whose success depends on obtaining a reasonable alignment between a given structural template and the protein sequence being analyzed. In order to leverage greater predictive power for proteins with few structural templates, we have developed a method to rank homology models based upon their compliance to secondary structure derived from experimental solid-state NMR...
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12-22-2011 06:50 AM
Uncovering symmetry-breaking vector and reliability order for assigning secondary structures of proteins from atomic NMR chemical shifts in amino acids
Uncovering symmetry-breaking vector and reliability order for assigning secondary structures of proteins from atomic NMR chemical shifts in amino acids
Abstract Unravelling the complex correlation between chemical shifts of 13 C α, 13 C β, 13 C�, 1 H α, 15 N, 1 H N atoms in amino acids of proteins from NMR experiment and local structural environments of amino acids facilitates the assignment of secondary structures of proteins. This is an important impetus for both determining the three-dimensional structure and understanding the biological function of proteins. The previous...
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11-14-2011 08:45 AM
4D prediction of protein 1H chemical shifts
4D prediction of protein 1H chemical shifts
Abstract A 4D approach for protein 1H chemical shift prediction was explored. The 4th dimension is the molecular flexibility, mapped using molecular dynamics simulations. The chemical shifts were predicted with a principal component model based on atom coordinates from a database of 40 protein structures. When compared to the corresponding non-dynamic (3D) model, the 4th dimension improved prediction by 6â??7%. The prediction method achieved RMS errors of 0.29 and 0.50 ppm for Hα and HN shifts, respectively. However, for individual proteins...
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01-09-2011 12:46 PM
[NMR paper] Secondary structural effects on protein NMR chemical shifts.
Secondary structural effects on protein NMR chemical shifts.
Related Articles Secondary structural effects on protein NMR chemical shifts.
J Biomol NMR. 2004 Nov;30(3):233-44
Authors: Wang Y
For an amino acid in protein, its chemical shift, delta(phi, psi)(s), is expressed as a function of its backbone torsion angles (phi and psi) and secondary state (s): delta(phi, psi)(s=deltaphi, psi)_coil+Deltadelta(phi, psi)_s), where delta(phi, psi)(coil) represents its chemical shift at coil state (s=coil); Delta delta(phi, psi)(s) (s=sheet or helix) is...
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11-24-2010 10:03 PM
[NMR paper] Improving the accuracy of NMR structures of large proteins using pseudocontact shifts
Improving the accuracy of NMR structures of large proteins using pseudocontact shifts as long-range restraints.
Related Articles Improving the accuracy of NMR structures of large proteins using pseudocontact shifts as long-range restraints.
J Biomol NMR. 2004 Mar;28(3):205-12
Authors: Gaponenko V, Sarma SP, Altieri AS, Horita DA, Li J, Byrd RA
We demonstrate improved accuracy in protein structure determination for large (>/=30 kDa), deuterated proteins (e.g. STAT4(NT)) via the combination of pseudocontact shifts for amide and methyl protons...
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11-24-2010 09:25 PM
[NMR paper] Secondary and tertiary structural effects on protein NMR chemical shifts: an ab initi
Secondary and tertiary structural effects on protein NMR chemical shifts: an ab initio approach.
Related Articles Secondary and tertiary structural effects on protein NMR chemical shifts: an ab initio approach.
Science. 1993 Jun 4;260(5113):1491-6
Authors: de Dios AC, Pearson JG, Oldfield E
Recent theoretical developments permit the prediction of 1H, 13C, 15N, and 19F nuclear magnetic resonance chemical shifts in proteins and offer new ways of analyzing secondary and tertiary structure as well as for probing protein electrostatics. For 13C,...
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08-21-2010 11:53 PM
[NMR paper] The chemical shift index: a fast and simple method for the assignment of protein seco
The chemical shift index: a fast and simple method for the assignment of protein secondary structure through NMR spectroscopy.
Related Articles The chemical shift index: a fast and simple method for the assignment of protein secondary structure through NMR spectroscopy.
Biochemistry. 1992 Feb 18;31(6):1647-51
Authors: Wishart DS, Sykes BD, Richards FM
Previous studies by Wishart et al. have demonstrated that 1H NMR chemical shifts are strongly dependent on the character and nature of protein secondary structure. In particular, it has been...
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08-21-2010 11:41 PM
PSSI: secondary structure from chemical shifts
Link to PSSI program
Reference and abstract:
Probability-based protein secondary structure identification using combined NMR chemical-shift data.
Wang Y, Jardetzky O.
Division of Chemical Biology, Department of Molecular Pharmacology, Stanford University, Stanford, California 94305, USA.
The predictive accuracy of secondary chemical shifts is more affected by protein seco
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