Description of the biological significance of topoisomerase I and the reaction it catalyzes

    Topoisomerase I is an enzyme that catalyzes the transport of individual strands of DNA through one another.  This works to alleviate the topological problems encountered by intracellular DNA (Chen, 1998).  Topoisomerase I removes the negative (and positive, in eukaryotic topoisomerase I enzymes) supercoils from DNA (Zhu, 1997).  This is an extremely important reaction that allows DNA replication to take place.

    Human topoisomerase I is of considerable biomedical importance because it is the sole target of camptothecin (CPT) family of anticancer drugs (Redinbo, 1998).   These drugs act by prolonging the lifetime of the nicked intermediate in the topoisomerase I reaction which are presumed to form obstacles to the advancement of transcription and replication complexes that eventually lead to DNA damage and cell death (Redinbo, 1998).

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Updated:  December 5, 1998

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