Novel strategy for the synthesis of template-assembled analogues of rat relaxin

The 'template-assembled synthetic protein' (TASP) concept provides a simple and elegant approach for the preparation of analogues that retain key stru ctural elements. We have synthesized TASP molecules containing the putative active site of relaxin, a peptide that has similar structural features to insulin but a markedly different biological role. Two types of chemoselecti ve thiol ligation strategies (thioether and thiazolidine) were used and com pared. The synthetic pendant peptides contain an essential region for bioac tivity that is located in the cc-helical region of the relaxin B-chain. Dep ending on whether the thioether or the thiazolidine chemistry was used to a ttach the peptides to the template, the reacting amino acid was placed eith er at the C-terminus or N-terminus, respectively, thus allowing the choice of orientation relative to the carrier molecule. The template molecule cons ists of a decapeptide with two proline-glycine turns and four evenly spaced lysine residues that were functionalized with the appropriate chemical moi ety. This allowed reaction with the appropriately derivatized peptides in s olution. To improve the template ligation step using the thioether approach , a pendant peptide C-terminal cysteamine residue was used to reduce potent ial steric hindrance during conjugation. The design of the peptides as well , as the synthetic strategy resulted in the acquisition of mimetics showing weak non-competitive and weak competitive antagonist properties. Copyright (C) 2000 European Peptide Society and John Wiley & Sons, Ltd.