This database is a collection of protein-protein homo- and hetero-complexes as well as domain-domain structures. This issue of the database contains 17.024 entries (as of October 2007) of which 1350 are two-chain protein hetero-complexes, 7773 homodimers and 1589 are one-chain proteins parsed into two domains (domain structures). The rest of entries are constructed from PDB files for multi-chain protein complexes by leaving only two interacting chains, (in the database nomenclature designators of those chains are appended to the name of the original PDB file).  The homo-complexes in this database are the complexes with two monomers having more than 95 % sequence identity. Each entry consists of the X-ray structure taken from the PDB data bank (in the PDB/ folder), sequence file (in the SEQ/ folder) and the data file (in the INF/ folder) where all relevant information is stored. File names consist of PDB ID and extensions .pdb (X-ray structures), .seq (sequence files or .inf (data files). Current implementation of the database accommodates the following  information for each entry, separately for larger (denoted as chain A^*) and smaller (chain B) components:

• Full sequence;
• Number of residues;
• Number of residues on the interface;
• List of interfacial residues;
• Number of helices and strands;
• Absolute (in Ų) and relative interface areas.

The database is searchable with respect to majority of the above parameters. Additional search is possible with respect to the PDB ID and protein names. Downloads are possible for both individual entries (as plain text files) and for the whole content or search (checked) result list (as one gzipped file). Supplementary search and download is available for the subset of the database at 40% sequence identity level (the DPPC40 database). Good luck and feel free to sent suggestions or comment by the clicking Send a comment button. Yes, and do not forget to enable Javascript in your browser, otherwise search engine will not work properly!

If usage of the database results to publication please quote the original paper**!

Other relevant resources for protein complexes and domains on Internet:

^* which, in general, may not coincide with the experimental chain designators in the PDB file.
^** P.J.Kundrotas and E.Alexov (2007) Nucleic Acids Res., v.35, pp. D575-D579.