A potent and selective agonist for NK-2 tachykinin receptor

Replacement of the glycine in position 8 of the C-terminal heptapeptide NKA(4–10) with β-alanine gives rise to a potent and selective agonist for the NK-2 tachykinin receptor. The affinity of [β-Ala 8]-NKA(4–10) to the NK-2 receptor is enhanced by almost one order of magnitude as compared to NKA(4–10), while affinity decreases at about the same extent at NK-1 and NK-3 receptors, respectively. Synthesis and biological activities of a series of NKA(4–10) analogues systematically replaced in each position with β-alanine are also reported.