title: [Effect of some nonintercalative antitumor drugs on the activity of calf thymus DNA topoisomerase I].
abstract: DNA topoisomerase I has been isolated from the nuclei of calf thymus by PEG fractionation and chromatography on P11 and on Bio-Rex 70. Either a positive or negative supercoiled pBR322 DNA can be relaxed by the enzyme. The activity of Topo I is Mg2+ and ATP independent. Some of nonintercalative antitumor drugs such as camptothecine, hydroxycamptothecine, cyclophosphamide, methotrexate and mitomycin C were found to inhibit the activity of Topo I. The results suggest that DNA Topo I can be used to screen new nonintercalative antitumor drugs as a target protein.
authors.affiliation: Department of Biology, Nankai University, Tianjin.
authors.forename: W S
authors.initials: WS
authors.lastname: Zhang
authors.forename: Z K
authors.initials: ZK
authors.lastname: Lin
authors.forename: X T
authors.initials: XT
authors.lastname: Huang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002417:Cattle; D003520:Cyclophosphamide / Q000494:pharmacology; D004264:DNA Topoisomerases, Type I / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D008727:Methotrexate / Q000494:pharmacology; D016685:Mitomycin; D008937:Mitomycins / Q000494:pharmacology; D013950:Thymus Gland / Q000201:enzymology
chemical_list: D000970:Antineoplastic Agents; D008937:Mitomycins; D016685:Mitomycin; D003520:Cyclophosphamide; D004264:DNA Topoisomerases, Type I; D008727:Methotrexate