Bax Group DC+ Server

SVD fit of RDCs to atomic coordinates icon

This server provides a Singular Value Decomposition (SVD) fit of the dipolar couplings to existing structure(s):

It uses the Order Matrix method of fitting the couplings via SVD to an existing static structure
It also performs a Single Tensor Ensemble Fitting to an ensemble of structures (un-weighted or variable-weighted)
It also provides Multi-Tensor Multi-Conformer Fit
It returns: the SVD-fitted alignment tensor parameters; the back-calculated couplings; the statistics (Q-factor, RMS ...) of the agreement between the input and the calculated couplings
It also includes various options for error analysis and cross-validation.

Constrained least-squares fit of RDCs to atomic coordinates icon

This server provides a constrained least-squares fit of an existing set dipolar couplings to an existing structure. It returns the couplings predicted by the fit, and the parameters of the alignment tensor determined by the fit. In the constrained fit, it is possible to select upper and lower limits or fixed values for the tensor magnitude, rhombicity, and orientation angles.

Predicts RDCs for known Saupe matrix and structure icon

This server calculates dipolar couplings :

for an existing structure when given order matrix tensor parameters (Saupe matrix) determined from a previous fit.
The couplings to calculate are specified in the form of a DC+ input table.
for an existing structure when given a complete set of tensor parameters in terms of Magnitude, Rhombicity, and rotational angles.
The couplings to calculate can be specified in the form of a DC+ input table or selected from one or more common classes, such as H^N-N, H^α-C^α, etc.

SVD fit of RCSA data to known structure (proteins only) icon

This server provides a Singular Value Decomposition (SVD) fit of the residual chemical shift anistropy (RCSA) to existing structure(s). It returns the parameters of the alignment tensor determined by the fit, the RCSA values predicted by the fit, and their agreements to the input RCSA data.

Helix-Fit icon

This server performs a SVD fit for dipolar couplings observed for a single α-helix, using a reference structure of the refined ideal α-helix or the known experimental α-helical structure.

Orthogonalize alignment tensors and RDCs icon

This server performs orthogonalization for a set of alignment tensors obtained from dipolar couplings measured at multiple alignment media, and generates (up to 5) sets of residual dipolar couplings that correspond to orthogonal alignment tensors.

Generate random peptide planes and RDCs icon

This server creates a PDB file containing only the atoms in the randomly orientated peptide planes, for the purpose of performing hypothesis testing of dipolar coupling analysis.
The peptide planes are arranged in a cubic grid.
The server also creates a DC+ table of synthetic couplings corresponding to the PDB file generated.
The random orientations are generated according to a random number seed. Use large integers for setting the random number seed, or value of 0 to set the random number seed according to the system clock.

DC+ Web Version icon

DC+ (web version) is an interactive RDC analysis tool for proteins and nucleic acids. Supports SVD, NLLS, restrained NLLS, simultaneous ensemble fitting, orthogonalization, RCSA, and comprehensive statistical validation.

	From the Bax Group at the National Institutes of Health DC+: Servers for Residual Dipolar Coupling Calculations