Approximately 1,000 mmCIF formatted files for nucleic acid-containing crystal structures are now available from the PDB beta ftp site at ftp://beta.rcsb.org/pub/pdb/uniformity/data/mmCIF/. These entries were curated by the Nucleic Acid Database project and revisited for data uniformity processing.
The files follow the latest version of the mmCIF dictionary supplemented by an exchange dictionary developed by the PDB and the European Bioinformatics Institute. This exchange dictionary can be obtained from http://pdb.rutgers.edu/mmcif/.
An application program called CIFTr is available for translating files in mmCIF format into files in PDB format. CIFTr works on UNIX platforms, and can be downloaded at http://pdb.rutgers.edu/software/. CIFTr also provides the option of producing a file with a blank chain ID field for structures with a single chain, and the option of producing files with standard IUPAC hydrogen nomenclature for standard L-amino acids.
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