The Protein Data Bank (PDB) is an archive of experimentally determined three-dimensional structures of proteins, nucleic acids, and other biological macromolecules [1, 2].

It is jointly managed by the Worldwide Protein Data Bank (wwPDB) partnership. The Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB) is funded by the National Science Foundation, National Institutes of Health, and US Department of Energy and serves as the US data center for the wwPDB.

162,041 structures in the PDB have a structure factor file. 11,242 structures have an NMR restraint file. 5,774 structures in the PDB have a chemical shifts file. Most structures are determined by X-ray diffraction, but about 7% of structures are determined by protein NMR.

The PDB is a structure database that contains the three-dimensional crystal structure of macromolecules that are experimentally determined (Berman et al., 2000). These experimental methods are X-ray crystallography and NMR spectroscopy and nowadays cryo-electron microscopy is also used.