Mammalian Neurokinins: Structure-Activity Study of the N- and C- Terminals

The analysis of the primary structures of three neurokinins, namely neurokinin P (NKP), neurokinin A (NKA) and neurokinin B (NKB) reveals not only major differences in the chemical structure of these peptides at their N-terminal region but also striking similarities of their carboxyl extremities. The N-terminal major difference is represented by the presence of two positively charged residues (ArgI and Lys3) in NKP while NKA contains only one such residue (Lys2) and NKB has none. The C-terminal extremities of the three neurokinins are very similar since all contain the tripeptide Gly-Leu-Met-NH₂.