PSSARD (2.0): a database server for making flexible queries relating amino acid sequences to main-chain secondary structure conformations for proteins of known three-dimensional structure and certain useful applications.

We have updated the Protein Sequence-Structure Analysis Relational Database (PSSARD) first published in the Int. J. Biol. Macromol. 36 (2005) 259-262 corresponding to 1573 representative protein chains selected from the Protein Data Bank (PDB). In this, the updated and revised PSSARD (Version 2.0), we have included all proteins in the Protein Data Bank available at the time of developing this database including the NMR PDB entries. The current database corresponds to 22,752 XRAY PDB entries and 3977 NMR PDB entries and is separated accordingly in order to facilitate the appropriate database search. The representative protein chains can also be separately accessed within the current database. We have made a provision to combine more than one field to query the database and the results of any search can be used to carry out further nested searches using a combination of queries. We have provided hyperlinks to the individual PDB entries obtained as the result of any search in PSSARD in order to obtain additional details relevant to the protein structure. Certain applications useful to identify domains and structural motifs are discussed.