bookmark RefDB / Re-referenced Protein Chemical shift Database Contains reference-corrected protein chemical shifts derived from the Biological Magnetic Resonance Bank (BMRB). RefDB was assembled by using the SHIFTX program to predict protein 1H, 13C and 15N chemical shifts from X-ray or NMR (nuclear magnetic resonance) coordinate data of previously assigned proteins. The predicted shifts were then compared with the corresponding observed shifts and a variety of statistical evaluations performed. In this way, potential mis-assignments, typographical errors and chemical referencing errors could be identified and corrected. This approach allows for an unbiased, instrument-independent solution to the problem of retrospectively re-referencing published protein chemical shifts.