English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Etoposide, a nonintercalating antitumor drug, is a potent inhibitor of topoisomerase II activity. When Trypanosoma equiperdum is treated with etoposide, cleavable complexes are stabilized between topoisomerase II and kinetoplast DNA minicircles, a component of trypanosome mitochondrial DNA (T. A. Shapiro, V. A. Klein, and P. T. Englund, J. Biol. Chem. 264:4173-4178, 1989). Etoposide also promotes the time-dependent accumulation of small minicircle catenanes. These catenanes are radiolabeled in vivo with [3H]thymidine. Dimers are most abundant, but novel structures containing up to five noncovalently closed minicircles are detectable. Analysis by two-dimensional gel electrophoresis and electron microscopy indicates that dimers joined by up to six interlocks are late replication intermediates that accumulate when topoisomerase II activity is blocked. The requirement for topoisomerase II is particularly interesting because minicircles do not share the features postulated to make this enzyme essential in other systems: for minicircles, the replication fork is unidirectional, access to the DNA is not blocked by nucleosomes, and daughter circles are extensively nicked and (or) gapped.

Mitochondrial topoisomerase II activity is essential for kinetoplast DNA minicircle segregation.