A series of dimeric analogs of neurokinin B (NKB) COOH-terminal heptapeptide were synthesized in order to find an optimum length of cross-linking spacer for bivalent interaction with tachykinin receptors. Dimerization was carried out at the NH 2-terminus of heptapeptide with succinyl bis [(Gly) n–OH], in which the number of glycine varies from 0 to 4. Dimers D– (Gly) n–NKB 4—10, namely succinyl bis [(Gly) n–Asp–Ser–Phe–Val–Gly–Leu–Met–NH 2]( ...