CONEXN - a procedure to generate ideal groups for stereochemically restrained refinement of protein models

A procedure has been developed to incorporate stereo-chemical restraints information for new groups into the dictionary of ideal groups used by the program PROTIN which prepares the input file needed by the reciprocal-space least-squares refinement program PROLSQ. It requires the availability of Cartesian coordinates for the group to be added to the dictionary, usually obtained from crystallographic analysis of crystals of the compound. If no such information is available these coordinates can be generated by an ancillary program, MOLBLD, which makes use of specified bond lengths, bond angles and dihedral angles to produce the required coordinates. The program is written in standard Fortran 77 and has been used in the refinement of several structures.