http://www.nih.gov/www94/molrus
The Molecules R US site provides an on-line engine for searching the Brookhaven Protein Data Bank (PDB) of both proteins and nucleic acids' crystallographic structures. The PDB is a repository of published crystal structures. The user can perform text-based searches of the database contents and display molecular structures if the local client is correctly configured. For the latter case, configuration instructions are provided on-line. Structure files in PDB format may be downloaded to the local host.