Relibase+ is a database search, retrieval and analysis system for protein-ligand complex structures. Relibase+ provides easy access to all such experimental structures within the Protein Data Bank (PDB) and, in addition, offers the facility for generating proprietary databases, searchable alongside the PDB.

Relibase+ is a powerful tool for investigating protein-ligand binding sites in individual complexes and trends through series of complexes in both publicly available and proprietary data.

Basic Relibase+ features include:

• An intuitive web-based user interface
• A relational database architecture that allows easy integration with institutional informatics systems
• Local installation for confidential searching
• Generation of proprietary databases, searchable alongside the PDB
• Standard text searching (including SMILES and SMARTS strings)
• 2D substructure searching
• 3D protein-ligand and protein-protein interaction searching
• Ligand similarity searching
• Clear and comprehensive 3D visualisation in Hermes, including the ability to view structures in stereo
• Automatic superposition of related binding sites to compare ligand binding modes, water positions, ligand-induced conformational changes, etc.

Advanced features include:

• Detailed analysis of superimposed binding sites including protein flexibility, ligand overlap, conserved water positions etc.
• Improved and enhanced treatment of hitlists (i.e. entries saved from Relibase+ searches), including the conversion of saved hitlists of ligand entries into lists of PDB entry codes and vice versa
• A crystal packing module enabling detailed investigation of crystallographic packing effects around ligand binding sites
• Detailed information about the water structure in each entry, e.g. notification of dubious water molecules, descriptors for individual water molecules and water-mediated protein-ligand contacts
• Functionality for detection of unexpected similarities amongst protein cavities (e.g. active sites) that share little or no sequence homology
• Secondary structure classification and searching according to a novel and comprehensive turn and helix assignment scheme
• Links to libraries of inter- and intramolecular geometry, for validating ligand-protein interactions and ligand conformations, are available for CSD System subscribers
• A command-line interface which allows access to PDB data and Relibase+ search methods from within the Python scripting language environment
• An interface to SuperStar, for prediction of protein-ligand interactions

Relibase+ is a client-server application.

• The server is supported on Linux platforms
• The client runs on popular web browsers on Windows and Linux operating systems

For a free evaluation of the whole Relibase+ package, normally available for those interested in purchase, please contact CCDC.

The web version, Relibase, which contains a subset of the above features but allows searching of the whole PDB database, continues to be maintained and is freely available to academic users.