[The antigen activity and structure of analogues and fragments of angiotensin, which contain enantiomeric forms of amino acids and aza-alpha'-homoamino acids].

The antigen activity of angiotensin, its fragments and analogues, which contain enantiomeric forms of amino acids and aza-alpha'-homoamino acids is studied by cross reactions with specific antibodies, obtained for angiotensin and its central tetrapeptide. It is found that the inclusion of additional NH-group between alpha carbon and carboxyl group of peptide chain, although in few cases radically changes spatial structure of compounds, does not deprivate their antigen activity. The replacement of NH-group to the C-end of the angiotensin molecule by affection the antigen determinant considerably decreases the antigen activity of the analogues. The important role in the determination of the antigen activity play the tyrosine residue and its specific orientation with respect to the antigen molecule. Low molecular weight fragments and analogues of the central part of angiotensin molecule, which have less "rigid" spatial structures, are capable to reorganize their spatial structure during interaction with antibodies.