[The effect of side radicals on the peptide structure. Surface of potential energy of model alanine and phenylalanine dipeptides].

The problem of stabilization of different dipeptide conformations is discussed within the fragment-fragment interactions method. It is shown, that the introduction of a CH3-group in glycine is a weak perturbation and for Ala-dipeptide the preferential structure remains C7 (like for glycine). On the contrary the introduction of a C6H5CH2-group in glycine is a strong perturbation and for Phe-dipeptide C5 becomes the preferential structure.