Description of peptide and protein secondary structures employing semiempirical methods

Novel semiempirical methods (OM1, OM2) have been employed to study typical elements of secondary structure in peptides and proteins. The calculated ge ometries and relative stabilities are discussed in comparison to correspond ing data from the ab initio MO theory and from the established semiempirica l methods AM1 and PM3, respectively. It is shown that the description of th e peptide conformers is considerably improved by OM1 and OM2 compared with AM1 and PM3, although in some cases there are still discrepancies with the ab initio data. (C) 2001 John Wiley & Sons, Inc.