Article: article from journal or magazin.
Human topoisomerase II-DNA interaction study by using atomic force microscopy.
Type II topoisomerases (Topo II) are unique enzymes that change the DNA topology by catalyzing the passage of two double-strands across each other by using the energy from ATP hydrolysis. In vitro, human Topo II relaxes positive supercoiled DNA around 10-fold faster than negative supercoiled DNA. By using atomic force microscopy (AFM) we found that human Topo II binds preferentially to DNA cross-overs. Around 50% of the DNA crossings, where Topo II was bound to, presented an angle in the range of 80-90°, suggesting a favored binding geometry in the chiral discrimination by Topo II. Our studies with AFM also helped us visualize the dynamics of the unknotting action of Topo II in knotted molecules.
DNA/chemistry, DNA/metabolism, DNA Topoisomerases, Type II/chemistry, DNA Topoisomerases, Type II/metabolism, Humans, Microscopy, Atomic Force, Nucleic Acid Conformation, Protein Binding, Protein Conformation
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