Study Of Solution Behavior Of Single-Stranded Human Telomeric DNA

Telomeres are complexes of proteins and DNA at the end of the eukaryotic chromosomes.The structure of such a complex plays an important role in protecting the chromosome and regulating the cell division cycle.In all vertebrates,telomere DNA consists of?1000 TTAGGG sequences and their corresponding complementary sequences to form a double-stranded DNA structure,and at the end of the double-stranded DNA,there is a single-stranded chain of?200 nucleotides in length.The research object of this thesis is to investigate the structure of single-stranded telomere DNAs.The single-stranded guanine(G)-rich telomere DNA sequence can form a continuous G-quadruplex structure under certain conditions.Due to the applications in the super-molecular chemistry of this structure,the designs of nano-devices,and the development of anti-cancer drugs,it has led to a wide range of research interests.We specifically studied the following aspects:We used the analytical ultracentrifuge(AUC)to study the effects of ions on the telomeric DNAs with different lengths,and then studied the structure of d[AGGG(TTAGGG)6](G6-DNA)at different concentrations in presence of potassium ion and found that monomer and dimers coexist in potassium ions solutions,and the intramolecular structure is more stable than the dimer G-quadruplex structure.Then the equilibrium constant was determined.Moreover,we characterized the effect of a single repeat of the human telomere d(TTAGGG)(Gol-DNA)on the monomer-dimer equilibrium by analytical ultracentrifuge(AUC),circular dichroism(CD),polyacrylamide gel electrophoresis(PAGE)and other methods.The reults show that G01-DNA can bind to the G-quadruplex structure of G6-DNA and form an additional G-quadruplex structure,and affect the monomer-dimer equilibrium of G6-DNA.We believe that this study is useful for understanding structure polymorphism of long single-stranded telomeric DNAs.