Conformational aspects of the structure-function relationships in the biologically active peptides

On the base of a semiempirical computational method is suggested a scheme to the study conformational aspects of structure-function relationships of biologically active peptides. As an example have been investigated the conformational properties of some monosubstituted analogs of the tachykinin neuropeptide, substance P, by theoretical conformational analysis method. Calculations indicated that the spatial structure of these synthetic analogs monosubstituted with L-alanine and D-alanine in the all positions may be described by set of low-energy conformations. Analysis of the geometric and energy parameters of these monosubstituted analogues demonstrated that amino acids, localized at the C-terminal heptapeptide sequence are important for the stabilization of the alpha-helical conformation.