Welcome to HIC-Up, the Hetero-compound Information Centre - Uppsala, a freely accessible resource for structural biologists who are dealing dealing with hetero-compounds ("small molecules").

This service is provided and maintained by Gerard Kleywegt at the Department of Cell and Molecular Biology, Uppsala University.

This site contains information about hetero-compounds encountered in files from the Protein Data Bank (PDB). It is updated once or twice a year.

If you use information from this site in your publications, please cite one of the following papers:

• Kleywegt, G.J. (2007). Crystallographic refinement of ligand complexes. Acta Cryst D63, 94-100 (CCP4 Proceedings). (PDF)

• Kleywegt, G.J., Henrick, K., Dodson, E.J., & van Aalten, D.M.F. (2003). Pound-wise but penny-foolish - How well do micromolecules fare in macromolecular refinement ? Structure, 11, 1051-1059. (PDF)

• Kleywegt, G.J. and Jones, T.A. (1998). Databases in protein crystallography. Acta Cryst D54, 1119-1131 (CCP4 Proceedings). (PDF)

For every compound, a subset of the following information is available:

• Coordinate files (PDB and text files)
• Visualisation files (Chime and VRML)
• Dictionary files (X-PLOR/CNS, O, TNT)
• Links to off-site databases and servers (PDBsum, EDS, PRODRG, Relibase, MSDchem, ChemDB, Jena HCD, etc.)
• Miscellaneous files and information

There are various ways in which you try to locate a particular compound:

• through the QuickXS mechanism
• by residue name (usually, a three-character abbreviation, e.g. REA for retinoic acid)
• by trivial name (e.g., benzene)
• by chemical formula (e.g., C6 H12 O6)
• by number of non-hydrogen atoms
• by index lists of chemical composition
• through search engines (Google, AltaVista)
• through other services (PDBsum, Relibase, PDB, etc.)
• using a connection table (CT; not implemented yet)

The first release of HIC-Up was in September, 1997. Prior to that, a repository with X-PLOR topology and parameter entries (automatically generated with XPLO2D) was maintained in Uppsala, with a mirror at Yale, and a separate repository with O-related information existed as well.

The number of entries in HIC-Up has developed as follows: