Multiple Synthetic Routes to the Mini-Protein Omomyc and Coiled-coil Domain Truncations.

The Myc transcription factor represents an “undruggable” target of high biological interest due to its central role in various cancers. An abbreviated form of the c-Myc protein, called Omomyc, consists of the Myc DNA-binding domain and a coiled-coil region to facilitate dimerization of the 90 amino acid polypeptide. Here we present our results to evaluate the synthesis of Omomyc using three complementary strategies: linear Fmoc SPPS using several advancements for difficult sequences, Native Chemical Ligation from smaller peptide fragments, and a high throughput bacterial expression and assay platform for rapid mutagenesis. This multi-faceted approach allowed access to up to gram quantities of the mini-protein and permitted in vitro and in vivo SAR exploration of this modality. DNA binding results and cellular activity confirm Omomyc and analogs presented here are potent binders of the E-box DNA engaged by Myc for transcriptional activation, and that this 90-amino acid mini-protein is cell permeable and ca...