The Protein Data Bank (PDB) file format is a textual file format describing the three-dimensional structures of molecules held in the Protein Data Bank, now succeeded by the mmCIF format.
The PDB format accordingly provides for description and annotation of protein and nucleic acid structures including atomic coordinates, secondary structure assignments, as well as atomic connectivity.
Its fixed-column width format is limited to 80 or 140[4] columns, which was based on the width of the computer punch cards that were previously used to exchange the coordinates.
The final update to the PDB file format was in November 2012 with version 3.30.
[6] A typical PDB file describing a protein consists of hundreds to thousands of lines like the following (taken from a file describing the structure of a synthetic collagen-like peptide):