THE PROTEIN PROGRAM SYSTEM: REAL SPACE TECHNIQUES USING FOURIER AND PATTERSON MAPS. Wolfgang Steigemann, Max-Planck-Institut frBiochemie, Computing Center, D-82152 Martinsried, Germany

Recently implemented modules and features in the PROTEIN program system will be in focus that provide high flexibility in the area of density modification and manipulation in real space.

Real space techniques have been an important issue in PROTEIN from its very beginning. Original goals of the "search methods" in the field of molecular replacement have been the correlation of maps for the exploration of non-crystallographic symmetry (Patterson self rotation), positioning of known molecular models in unknown structures (cross rotation, translation) both in Patterson and Fourier map, location and refinement of local axes in Fourier map, calculation of "mean Fourier maps", and rotated density maps.

The widely used density modification techniques like molecular averaging and solvent flattening aiming at phase improvement and interpretability of density maps have required further extension and flexibility of these capabilities. Following the principles of PROTEIN, this has been acchieved by implementing additional modules and features (e.g. simple map algebra incl. rotation and superposition, unit-cell generation from an asymmetric unit, mask calculation by convolution techniques). In this way tools are provided to the user he can combine with the already present elements to powerful procedures on the level of PROTEIN's flexible command language.

PROTEIN itself has been ported to a variety of platforms and is available for the most prominent Unix systems incl. DEC Alpha, Silicon Graphics, IBM RS/6000, Sun and Hewlett Packard, as well as OpenVMS on VAX and AXP,.on particular request

The Web page http://www.biochem.mpg.de/PROTEIN/home.html provides detailed information about the packages capabilities, availability, new features, examples, a mailing list for the user community, etc.