No abstract

A novel inhibitor of topoisomerases designated as topostatin was isolated from the culture filtrate of Thermomonosporaalba strain No. 1520. The inhibitory activity of topostatin was shown to be pH-and temperature-dependent with a maximum around at pH 6 and 28°C. The stability of topostatin decreased with decreasing pH and rising temperature. Topostatin inhibited topoisomerases I and II in a competitive manner with respect to DNA.The inhibitor also inhibited some restriction endonucleases such as Sea l, Hindlll and PstI, but not AluI, BamHI, EcoRI, RNase A, DNase I, DNase II and DNA ligase. Topostatin did not induce the nuclear accumulation of p53 protein by DNAdamage in the normal humancells.

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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.