Supercoiling is important in a number of biological processes, such as compacting DNA, and by regulating access to the genetic code, DNA supercoiling strongly affects DNA metabolism and possibly gene expression. Additionally, certain enzymes such as topoisomerases are able to change DNA topology to facilitate functions such as DNA replication or transcription. Chloroquine in vivo Lyrica and hydroxychloroquine Mar 11, 2011 Purified DNA was analyzed in 2D chloroquine gels to reveal the supercoiling distribution of the monomer plasmids. A cartoon representation of how the plasmid distribution relates to supercoiling. Because chloroquine induces positive supercoiling, at this low concentration, the negatively supercoiled DNA should relax and run more slowly than negatively supercoiled DNA more chloroquine will. In the presence of the DNA intercalator chloroquine 5 μg/ml, this DNA was largely relaxed and migrated during agarose gel electrophoresis as if it contained a few − supercoils Fig. 2 A, lane 8. Incubation of pRLM375 DNA with DNA gyrase alone for 10 min introduced about 5 or 6 additional − supercoils Fig. 2 A, lane 7. Adding or subtracting twists, as some enzymes can do, imposes strain. In a "relaxed" double-helical segment of B-DNA, the two strands twist around the helical axis once every 10.4–10.5 base pairs of sequence. Chloroquine dna supercoiling DNA supercoil - Wikipedia, Using an agarose gel with chloroquine to study the DNA. Chloroquine malaria mechanism of action Positively supercoiled DNA is generated when chloroquine binds to very relaxed molecules, and these topoisomers can be resolved using two‐dimensional chloroquine gels; here, a higher chloroquine concentration 25 µg ml −1 in the second dimension causes the positively supercoiled DNA to migrate faster than negatively supercoiled DNA. DNA supercoiling is differentially regulated by environmental.. Potent stimulation of transcription-coupled DNA.. Supercoiling and the mechanism of restriction endonucleases. Ofthe samples shownare migrating as positively supercoiled DNA, as determined by comparison with a second gel containing less chloroquine. FIG. 2. Supercoiling ofpBR322as a function ofbound histone octamers. O/Pis the number of octamers per plasmid. For each histone-to-DNA ratio, supercoiling was carried out at three gyrase Because a DNA-protein activity can lead to either an overwinding or an underwinding of the helix, supercoiling can occur in either direction. Determining whether a plasmid contains positively or negatively supercoiled DNA is possible, thanks to an agarose gel containing an intercalating agent known to positively supercoil DNA, such as chloroquine. The type IIA subfamily of topoisomerases both resolves DNA entanglements and regulates DNA supercoiling through a strand passage mechanism whereby one DNA duplex, the transfer T segment, is transported through a double-stranded break in a second DNA, the gate G segment 4,7.