Telomeres are closely related to cell aging

death and canceration.Guanine-rich and cytosine-rich strands of human telomeric DNA can form G-quadruplex and I-motif conformation

respectively.These conformations have relations with telomerase activity

centromeric DNA structures

RNA intercalated structures

having been an attractive drug target for cancer chemotherapy and for modulation of gene transcription.In this paper

key factors to the formation of different conformations are studied by using circular dichroism spectrum(CDS).The results show that the formation of dAG3(T2AG3)3 into G-quadruplex is greatly affected by metal ions

while the I-motif structure of d(C3TA2)3C3T depends largely on pH values.It is easy to form WC duplex structure in the equimolar mixture of dAG3(T2AG3)3and d(C3TA2)3C3T

however

G-quadruplex and I-motif can both exist under certain conditions.