Double-Clicking Peptides onto Phosphorothioate Oligonucleotides: Combining Two Proapoptotic Agents in One Molecule

摘要

Described here is a method for the conjugation of phosphorothioate oligonucleotides (PSOs) with peptides. PSOs are key to antisense technology. Peptide-PSO conjugates may improve target specificity, tissue distribution, and cellular uptake of PSOs. However, the highly nucleophilic phosphorothioate structure poses a challenge to conjugation chemistry. Herein, we introduce a new method which involves a sequence of oxime ligation and strain-promoted [2+3] cycloaddition. The usefidness of the method was demonstrated in the synthesis of peptide-PSO conjugates that targeted two suppressors of both the intrinsic and the extrinsic pathway of apoplosis. It is shown that the activity of a PSO sequence targeted against mRNA from c-Flip can be enhanced by conjugation with a peptide mimetic, designed to inhibit the X-lmked inhibitor of apoptosis protein (XIAP).