SHELX applications to macromolecules

Direct methods inspired by Shake & Bake involving iteration between real and reciprocal space are able to solve structures with several hundred independent atoms, but still require data to atomic resolution (about 1.2 Angstrom). It is planned to add a new program, SHELXD, incorporating such algorithms in a future release of the SHELX system. Initial trials of the preliminary test version of SHELXD have been reasonably successful, and include the ab initio solution of several large 'small-molecules' that had resisted attempts using previous version of SHELXS, as well as the ab initio solution of three unknown (and several known) proteins from the native data alone.