OMEGA: a three-dimensional databank for protein structures (a complement to PDB).

OMEGA is a compilation of recent structural information on proteins derived from X-ray crystallography or NMR and published in journals referenced by Current Contents. To date, 401 entries have been included (334 X-ray, 28 NMR, 5 NMR + X-ray, 5 electron microscopy, 3 neutron scattering, 2 neutron diffraction, 1 electron microscopy + X-ray, 12 model, 11 miscellaneous), with 5-10 new proteins being added each week. OMEGA can be accessed on Macintosh and is interrogated through 32 key words (space group, resolution, secondary structure, number of residues, etc). This pool of proteins could be used for various purposes, including searches for proteins with a particular set of secondary structures. OMEGA will be continuously updated (every 6 months) and may later include all proteins already reported in the PDB, as well as structures reported in journals with smaller readerships.