The key factors in conformation of telomeric DNA

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.