Resonance : Reference Chemical Shifts

Graphs and Charts of Database Chemical Shift Data

This popup window presents the user with the distributions of known chemical shift values, for various kinds of atom, as they appear in the BioMagResBank or re-referenced RefDB databases. This information is useful when attempting to determine the type of a residue from its NMR spectra, for example when performing protein sequence assignment.

The popup is divided into two tabs for two different kinds of graphical display. The first “1D graphs” tab shows the distributions of chemical shift value for either hydrogens or other “heavy” atoms within a given kind of residue. The buttons that carry atom names above the main graph can be toggled two switch the display for different kinds of atom on or off.

The second “Amino Acid CA CB” tab is a special display to assist in the assignment of protein sequences when using triple-resonance experiments like HNCA/CB. Data for all of the common amino acids is displayed, but only for the alpha and beta carbons.

Caveats & Tips

Two dimensional correlations, e.g. between a 1H resonance and a covalently bound 13C will be added to Analysis in the future.

DNA and RNA chemical shift distributions is not present in the RefDB data, but are present in the BMRB data; to view the BMRB data change the pulldown menu at the top-right.

Some of the atom types have a second, minor chemical shift distribution, far from the main peak, that is erroneous (this data is still present in the source databases). An example of this is for the NE atom of the amino acid arginine at around 115 ppm, which in this instance is probably caused by peaks being assigned in HSQC spectra in the normal backbone amide ppm range when the NE peak is really an aliased harmonic and should be a spectrum width away, nearer 85 ppm.

Distributions that are notably jagged, due to lack of data for a given atom type should naturally not be relied upon to any great degree.

Main Panel

pulldown Source Database: Whether to use chemical shift data from the BMRB (unfiltered) or RefDB sets

button Clone: Clone popup window

button Help: Show popup help document

button Close: Close popup

1D Graphs

Simple graphs of how chemical shift values are distributed for a given atom type

pulldown Molecule Type: Which of the common bio-polymer types to show data for

pulldown Residue Code: Which residue code to show chemical shift distributions for

pulldown Atom Type: Whether to show distributions for hydrogen atoms or other atoms

selector *None*: The selection of atom name to display distributions for

Scrollbar: :

Amino Acid CA CB

Density plots of alpha a & beta carbon shift distributions for common amnio acids

Scrollbar: :

Table Of Contents

Previous topic

Resonance : Measurement Lists

Next topic

Chart : Chemical Shifts Table

This Page