THIS INFORMATION IS OBSOLETE AND IS PROVIDED ONLY FOR ITS HISTORICAL VALUE

by Graham M. Smith, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065

This program was written to provide a method for exhaustively searching for all acceptable conformations for a given ring in a molecular model (it was written to work in connection with the Merck Molecular Modeling System). For input, the program reads a modeling system format file of the structure to be studied and prompts the user with a series of questions intended to obtain information needed to set up the specific bond rotations which are to be made in the course of the search. It is at this point that the user may enter information derived from NMR work, in the form of dihedral angles derived from coupling constants and non-bonded contacts derived from NOE experiments. Experimental data can be used to limit greatly the size of the search. For those bonds which cannot be constrained by experimental data, the program will rotate each in turn by small incremental steps, producing all possible conformations which are tested to see if they still form a ring. There are several geometric checks made during the course of this search which result in very high efficiency.

The program is first run interactively to set up a "control" file which is read by the program on submission to the batch queue where the processing can take from several minutes to several hours. The output from the program is in the form of a summary of the results of the search and a file containing all of the acceptable structures found during the search. These structures are in the modeling system format and can be directly submitted to energy minimization or further processed to remove "duplicates" before the energy minimization step.

The intent of this work was to provide a method that would allow medium-size rings (8 to 22 members) to be studied and to give the user some assurance that the lowest energy conformation for the ring had been found. This program was originally developed for use in modeling the cyclic hexapeptide structures in the somatostatin analog project but was written so as to be usable on other structures.

FORTRAN 77 (VAX) Lines of Code: 11,909