Peptide Ligations by Using Aryloxycarbonyl-o-methylaminoanilides: Chemical Synthesis of Palmitoylated Sonic Hedgehog.

A simple procedure for C-terminal activation of peptides in solution and its application in native chemical ligation and protein synthesis is described. This method involves a mild thioesterification based on the conversion of an aryloxy-o-methylaminoanilide to thioester under aqueous conditions and in situ ligation with an N-terminal cysteine peptide. The versatility is shown in pH-controlled sequential ligations. To illustrate the usefulness of this methodology, we synthesized the palmitoylated N-terminal domain of human Sonic Hedgehog, a morphogen protein that binds the transmembrane receptor Patched and activates the Hedgehog signaling pathway, involved in embryonic development and in the proliferation of multiple tumors. This approach extends the chemical toolset of chemical protein synthesis based on o-aminoanilide and o-methylaminoanilide peptides.

Syntheses of aminoalcohol-derived macrocycles leading to a small-molecule binder to and inhibitor of Sonic Hedgehog.

We report the synthesis and biological activity of a library of aminoalcohol-derived macrocycles from which robotnikinin, a binder to and inhibitor of Sonic Hedgehog, was derived. Using an asymmetric alkylation to set a key stereocenter and an RCM reaction to close the macrocycle, we were able to synthesize compounds for testing. High-throughput screening via small-molecule microarray (SMM) technology led to the discovery of a compound capable of binding ShhN. Follow-up chemistry led to a library of macrocycles with enhanced biological activity relative to the original hit compounds. Differences in ring size and stereochemistry, leading to alterations in the mode of binding, may account for differences in the degree of biological activity. These compounds are the first ones reported that inhibit Shh signaling at the ShhN level.