Lego_Ca [id two atoms] or [mol res1 res2]
Look through the fragment database to find similar pieces of structure. A dial becomes activated to pass through the top 20 best fits. The rms fit, protein and sequences are shown on the prompt window. The user is also able to specify any particular protein in the data base. Use Yes/ No to pick the best matching main chain fit to one's own CA atoms. Only the main chain atoms are extracted from the database. The coordinates of the first and last residues in the user's zone are not affected.