CIF applications. XI. A La Mode: a ligand and monomer object data environment. I. Automated construction of mmCIF monomer and ligand models

The macromolecular Crystallographic Information File (mmCIF) dictionary [Fi tzgerald et al. (1997). The Macro-molecular Crystallographic Information Fi le Dictionary, http://ndbserver.rutgers.edu/mmcif] provides a comprehensive description of chemical components used as models in the crystallographic refinement of macromolecular structures. A new ligand and monomer object da ta environment named A La Mode is described for building chemical-component models in the mmCIF representation from surveys of high-resolution small-m olecule crystal structures. Examples of the application of this system are presented for an intercalating drug component and for a nucleotide unit con structed from independent base, sugar and phosphate components.