G-quadruplex (G4) is one of the non-canonical nucleic acid structures that regulate multiple key biological processes. The formation of G4 hinders the progression of cancer. The molecular entities which can stabilize the G4 structure are very important to design anticancer therapeutics. Herein, it is described that a synthetic dendron-like peptide, C δ3 -(YYEE)-E co-assembles with G4 DNA in aqueous buffer containing Na + ions. Various orthogonal biophysical studies have established the co-assembly phenomenon. In silico, molecular docking studies also corroborate the results obtained from biophysical experiments. Importantly, the co-assembly enhances the thermal stability of G4 DNA compared to free G4 DNA. The peptide inhibits the activity of telomerase enzyme which is found to be over-expressed in most of the cancer cells and also downregulates the c-Myc oncogenic expression. The peptide exhibits significant cytotoxic effect on cancer cells (HeLa and U2OS) compared to non-cancer cells (HEK293) under similar experimental conditions. The study highlights the applicability of a synthetic bioactive peptide as a putative anticancer therapeutic.

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