DNA Topoisomerase II Poisons and the Cell Cycle

摘要: Nuclear DNA, a target for many anticancer drugs, does not exist inside human cell as an extended, relaxed and unrestrained molecule. Rather, in its protein-associated form of chromatin it is highly organized with order being imposed by specific DNA-protein interactions. The imposition such restraints on the free movement DNA molecules within nucleus means that any topological problems must be actively resolved topoisomerase enzymes (1). major type II enzyme, II, strategically located at base loop domains to carry out housekeeping functions operates forming temporary gates double stranded (Fig. 1) through which intact helix can pass. Several classes antitumor drugs are now recognized poisons because their ability trap enzyme stabilized cleavable complexes 1).