DNA condensation induced by a cationic polymer studied by atomic force microscopy and electrophoresis assay.
We synthesized a cationic polymer, poly(PEGMA)-4N, which has brush-like chains and four positively charged amino groups at the end of the molecules. DNA condensation induced by poly(PEGMA)-4N was investigated through electrophoresis assay by its ability to retard DNA mobility and to inhibit HindIII enzyme cleavage. The detailed structures of DNA condensates induced by poly(PEGMA)-4N were observed through atomic force microscopy (AFM). Interactions between polymers and DNA are mainly attributed into depletion effect and electrostatic interaction. Positively charged amino groups in poly(PEGMA)-4N interact with DNA through electrostatic interaction, and depletion effect also takes effect because poly(PEGMA)-4N is a flexible polymer. Comparing the contributions that the two interactions gave in DNA condensation process, we found that depletion effect played a major role compared with electrostatic interaction.
Hou
Sen
S
College of Life Science, Nankai University, Tianjin, PR China.
Yang
Kun
K
Yao
Yang
Y
Liu
Ze
Z
Feng
Xizeng
X
Wang
Rui
R
Yang
Yanlian
Y
Wang
Chen
C
D004247:DNA / Q000737:chemistry*; D004587:Electrophoresis, Agar Gel; D008689:Methacrylates; D018625:Microscopy, Atomic Force; D011092:Polyethylene Glycols
D008689:Methacrylates; C531046:poly(PEGMA)-4N; D011092:Polyethylene Glycols; D004247:DNA