[Conformational analysis of tachykinins. III. C-terminal fragment Asx-Xaa-Phe-Yaa-Gly-Leu-Met-NH2].

Theoretical conformational analysis of C-terminal fragments of tachykinin peptides with a common amino acid sequence Asx-Xaa-Phe-Yaa-Gly-Leu-Met-NH2 suggested the conformational states to be independent of the nature of Xaa and Yaa residues. It is shown that among plausible spatial forms of the C-terminal fragments an alpha-helix with the hydrophobic coat consisted of identically oriented side chains is energetically the most stable structure. The preference of this conformation for tachykinins functioning is discussed.