G4 DNA present at human telomeric DNA contributes toward reduced sensitivity to γ-radiation induced oxidative damage, but not bulky adduct formation.

Human telomeric repeat sequence when present on plasmids can fold into G-quadruplex DNA structures, and can protect the DNA against IR induced DNA strand breaks and oxidative damage. These results in conjunction with our previous studies suggest that telomeric repeat sequence imparts less sensitivity to IR and thus telomeres of chromosomes are protected from radiation.