Circular dichroism spectroscopic studies on structures formed by telomericDNA sequences in vitro

Telomere plays an important role in cellular processes, such as cell aging, death and carcinogenisis. Having special sequences, it can form quadruplex structure in vitro. Circular dichroism (CD) spectroscopic studies show tha t TTAGGG, (TTAGGG)(2) and (TTAGGG)(4) can all form quadruplex in vitro and exist mainly as parallel quadruplex without metal ions. Both K+ and Na+ can stabilize the tetrameric structure and facilitate the forming of anti-para llel conformation. Furthermore, the conformations of quadruplex can also be affected by sequence length, the nature and concentration of metal ions.