CheShift has been developed to predict ¹³C^α chemical shifts of protein structures. It is based on the generation of 696,916 conformations as a function of the torsional angles for all 20 naturally occurring amino acids. Their ¹³C^α chemical shifts were computed at the DFT level. For further details on the CheShift ¹³C^α chemical shift predictions please read reference 4. The description of the visual, per residue validation, was discused in reference 1. Other references related to the method and its applications are listed below.

1.- Martin O.A. Vila J.A. and Scheraga H.A. CheShift-2: Graphic validation of protein structures. Bioinformatics 2012 (Submited).
2.- Vila, J. A., Serrano, P., Wüthrich, K., & Scheraga, H. A. Sequential nearest-neighbor effects on computed (13)C (alpha) chemical shifts. J Biomol NMR 2010, 48(1), 23-30.
3.- Martin, O. A., Villegas, M. E., Vila, J. A., & Scheraga, H. A. (2010). Analysis of 13Calpha and 13Cbeta chemical shifts of cysteine and cystine residues in proteins: a quantum chemical approach. J Biomol NMR 2010, 46(3), 217-25.
4.- Vila J.A., Arnautova Y.A., Martin O.A. and Scheraga H.A. Quantum-Mechanics-Derived ¹³C^α Chemical Shift Server (CheShift) for Protein Structure Validation. Proc Natl Acad Sci USA 2009, 106(40), 16972-16977.
5.- Vila J.A. and Scheraga H.A. Assessing the Accuracy of Protein Structures by Quantum Mechanical Computations of ¹³C^α Chemical Shifts. Acc Chem Res 2009, 42(10) 1545-53..
6.- Villegas M.E.; Vila J.A.; Scheraga H.A. Effects of Side-Chain Orientation on the ¹³C Chemical Shifts of Antiparallel β-sheet Model Peptides. J Biomol NMR 2007, 37, 137-146.
7.- Vila J.A.; Villegas M.E.; Baldoni H.A.; Scheraga H.A. Predicting ¹³C^α chemical shifts for validation of protein structures. J Biomol NMR 2007, 38, 221-235.
8.- Vila J.A.; Arnautova Y.A.; Scheraga H.A. Use of ¹³C^α chemical shifts for accurate determination of β-Sheet structures in solution. Proc Natl Acad Sci USA 2008, 105, 1891-1896.
9.- Vila, J. A.; Aramini J. M.; Rossi P.; Kuzin A.; Su M.; Seetharaman J.; Xiao R.; Tong L.; Montelione G. T.; H. A. Scheraga. Quantum Chemical ¹³C Chemical Shift Calculations for Protein NMR Structure Determination, Refinement, and Validation. Proc Natl Acad Sci USA 2008, 38, 14389-14394.
10.- Vila J.A.; Scheraga H.A. Factors affecting the use of ¹³C^α chemical shifts to determine, refine, and validate protein structures. Proteins 2008, 71, 641-654.
11.- Arnautova Y.A., Vila J.A., Martin O.A. and Scheraga H.A. What can we learn by computing ¹³C^α chemical shifts for X-ray protein models? Acta Cryst D 2009, D65, 697-703.