[Synthesis and analysis of conformationally restricted analogs of peptide inhibitors of the angiotensin-converting enzyme].

To investigate conformations of peptide inhibitors of the angiotensin-converting enzyme in the enzyme-inhibitor complex, the synthesis, studies of inhibitory activity, and conformational calculations of analogues of bradykinin-potentiating peptides with N-methylalanine or D-alanine in place of L-proline or L-alanine residues have been carried out. All the analogues showed a sharp decrease of inhibitory activity in comparison with the natural peptides, that might be considered as an indirect confirmation of the earlier proposed "conformation of inhibition" of the above-mentioned peptides.