Efficient search for all low energy conformations of polypeptides by Monte Carlo methods

The Metropolis Monte Carlo method has been added to the program FANTOM for energy refinement of polypeptides and proteins using a Newton–Raphson minimizer in torsion angle space. With this extension, different strategies for global minimization of the semiempirical energy function ECEPP/2 by various temperature schedules and restriction of conformational space were tested for locating local minimum conformations with low energy of the pentapeptide Met‐enkephalin. In total, 1881 conformations below −10 kcal/mol were found. These conformations could be represented by 77 nonidentical conformations which were analysed for their pattern of hydrogen bonds, types of tight turn, pairwise root‐mean‐square‐deviation (rmsd), Zimmermann codes and side chain conformations. All low energy conformations below −10.4 kcal/mol show strong similarity to the global minimum conformation in the backbone structure.