LAUSR

The structures of human telomeric DNA have received much attention due to its significant biological importance. Most studies have focused on G-quadruplex structure formed by short telomeric DNA sequence, but little is known about the structures of long single-stranded telomeric DNAs. Here, we investigated the structure of DNA with a long sequence of d[AGGG(TTAGGG) $_6$ ] (G $_6$ -DNA) and the effect of a single repeat sequence d(TTAGGG) (G $_{01}$ -DNA) on the structure of G $_6$ -DNA using sedimentation velocity technique, polyacrylamide gel electrophoresis, circular dichroism spectroscopy, and UV melting experiments. The results suggest that the G $_6$ -DNA can form dimers in aqueous solutions and G $_{01}$ -DNA can form additional G-quadruplex structures by binding to G $_6$ -DNA. However, G $_{01}$ -DNA has no effect on the structure of DNA with a sequence of d[AGGG(TTAGGG) $_3$ ] (G $_3$ -DNA). Our study provides new insights into the structure polymorphism of long human single-stranded telomeric DNA.